Anne Stavely, a fellow chorister and romantic interest of Morse, is found hanged at her home in Jericho. Presumed to be suicide, Morse isn’t so sure and investigates, despite not initially being assigned to the case. In searching for a suicide note at her home Morse is apprehended by Sergeant Lewis, beginning their lifelong partnership.

After convincing DCS Strange that he is not involved in Stavely’s death, and the promotion of DCI Bell to superintendent, Morse takes on the case. It transpires that the suicide note was taken by neighbour George Jackson, who uses its contents to extort money from Alan and Tony Richards, Stavely’s former employers.

At a gathering of his choir shortly after Anne’s death Morse is introduced to Alan Richards, providing the latter with a cast-iron alibi when Jackson is found to have been murdered at the same time.

Morse is distracted by the presence of Oedipus Rex on Stavely’s bedside table and theorises that Ned Murdoch, a local musical prodigy taken under Stavely’s maternal care, was the cause of her death.

Lewis is sent to follow up whether Murdoch is in fact Stavely’s son that she gave up for adoption, and take fingerprints of Tony and Adele Richards, but both come to naught; Stavely’s son lives in Wales and neither fingerprints match any taken from the Jackson murder.

When Nicholas Quinn, a deaf member of Oxford’s Foreign Examinations Syndicate, is found dead at his home Morse presumes murder and Quinn’s fellow syndics soon become suspects.

The movements of the staff on the Friday afternoon in question are all investigated by Morse and Lewis including Martin, Roope, Ogleby, the Secretary Bartlett and the attractive divorcee Monica Height who invariably catches Morse’s eye too. Noakes, the janitor, swears he saw Quinn leave the syndicate late on Friday evening but in reality he only saw a man in Quinn’s coat drive away in his car.

Ogleby seems most suspicious under questioning, although Morse is delighted to discover his alter ego is the crossword setter Daedalus with whom Morse has tested his wits against for years, but almost immediately afterwards Ogleby is found brutally murdered.

By now, Morse and Lewis have surmised that the cause of at least one of the murders is the illicit disclosure of exam papers to the education department of Al-Jamara by Quinn’s predecessor Bland, a practice that Quinn discovered and presumably disclosed to Ogleby. When Quinn was killed, Ogleby took it upon himself to investigate and suffered a similar fate at the killer's hands.

Martin’s infidelity with Height and a screening of Last Tango in Paris which they and Dr Bartlett all seem to have attended add a layer of confusion and deception to the proceedings, but soon Morse confidently arrests Roope in connection with Quinn’s murder.

Roope however has an alibi; he only arrived back in Oxford late on the Friday afternoon and met the Dean of Lonsdale College on the platform. He is therefore subsequently released without charge.

But when he rendezvouses with Dr Bartlett soon after Morse pounces again and, with some fanfare, arrests both of them in connection with the murders, suspecting that Dr Bartlett needed the illicit income stream to pay for treatment for his mentally unwell son.

Morse and Lewis are called to St Oswald’s where the churchwarden, Harry Josephs, has been seemingly stabbed by a local vagrant following a service. But it transpires that things might not be as they seem when Max the pathologist informs Morse that the man had enough morphine in his system to kill him before the knife even entered his chest. While the hunt for the vagrant begins, the vicar, Lionel Pawlen, and his congregants, are all eyed with suspicion.

Tipped off by another vagrant that the missing prime suspect may be in fact the vicar’s brother, Morse invites Pawlen in for questioning but he summarily throws himself off the church’s steeple instead.

Meanwhile Morse takes a romantic interest in the church caretaker, Ruth, who seems amenable to the attention but is somewhat evasive.

The bodies soon begin to pile up as Paul Morris, the organist, Brenda Josephs, with whom he has been having an affair, and even Morris’ son are all found dead and Morse is no closer to solving any of the crimes.

Eventually, with Ruth one of the only congregants left alive Morse, by chance, is scouting out the church once more when she enters and is soon confronted by a mysterious man, a man with whom we know she is intimately acquainted but who attempts to strangle her nonetheless. Morse awkwardly attempts a rescue and a struggle ensues resulting in a confrontation at the top of the church’s steeple. Morse, we earlier discovered, is afraid of heights.

While this psychopathic killer tries to put an end to Morse, Lewis rushes in to hit him over the head and watch him stumble over the edge to his death.

As they take the final body away it is only Morse who has realised who this killer is; Harry Josephs, the original ‘victim’ who never was.

And so it is revealed that Lionel Pawlen and his congregants were all in on the original murder, that of Lionel’s brother, Simon Pawlen, the vagrant. Simon had been left out of a great inheritance from an aunt due to his alcoholism and wayward lifestyle and had grown vindictive against Lionel as a result, spreading rumours about the vicar’s behaviour towards choir boys that had forced him out of his previous parish.

The original murder, then, was an elaborate way of getting rid of Simon, and Lionel used an invented church service, The Feast of the Conversion of St Augustine, and his congregants as co-conspirators, with whom he would share his wealth, to execute the plan.

A tour group of geriatric Americans descend on the Randolph Hotel, including a lady who is about to donate a priceless artefact, the ‘Wolvercote Tongue’, to the Ashmolean Museum. When she is found dead shortly after arriving and the Tongue is missing from her hotel room Morse suspects foul play, despite the doctor’s insistence she died from natural causes.

The chief suspect, Eddie Poindexter, the dead woman’s husband, soon goes missing and Morse and Lewis’ attention is diverted to Theodore Kemp, the colourful museum curator whose naked body is found floating in the River Cherwell the following evening.

Morse is convinced he now has two murders on his hands, both connected to the theft, but his guesswork is mere speculation. Kemp’s disabled wife commits suicide after learning of his death and Morse finally stumbles into a fruitful line of inquiry by considering the movements of the other expert connected to the tour, Cedric Downes, and his wife, who Morse and Lewis happen to intercept as she makes her way to London with a suitcase.

When they confront Downes on the platform of Oxford station later the same day, and his account of his awareness of Kemp’s death doesn’t match with his wife’s, he’s taken in for questioning. That’s not before he literally bumps into Poindexter, who coincidentally steps off a train as Downes attempts to make an escape.

The confessions from Poindexter and Downes are forthcoming. Poindexter admits that his wife’s death, unsurprising given her heart condition, occurred in his presence and that he took the Tongue in order to throw it away and collect the insurance money. His disappearance was also for the purposes of connecting with his long lost daughter.

Downes claims that Kemp’s death was an accident and occurred after a confrontation when he had returned home to collect his notes for his lecture, only to find his wife with Kemp in flagrante. With a little bending of the truth from Morse, he also admits to subsequently killing his wife while she was disposing of Kemp’s clothing in London.

As the episode comes to a close the Wolvercote Tongue is retrieved from the river and Morse admits that, despite his prior insistence, there were two cases here rather than one; the original death was simply of natural causes and the subsequent murders were not related to the theft at all.

Valerie Craven, the daughter of a local building magnate has been missing for six months and so an otherwise idle Morse is assigned the case.

When a letter arrives, purportedly from the missing girl, with a London postmark, initial inquiries take Morse and Lewis in the direction of a man named Maguire, a one-time boyfriend of Valerie. Reckless guesswork from Morse surprisingly strikes home and it is established that the girl is or at least was pregnant.

Further investigation centres on Valerie’s school and a head-strong headmaster, Donald Phillipson, and a former teacher now moved on, David Acum, are added to the suspect list.

When the deputy head, Cheryl Baines, is found dead at her home both Lewis and Strange lash out at Morse, whose prior insistence that murder was involved now seems confirmed.

Unexpectedly it is Phillipson’s wife, Sheila, who is identified by a neighbour as being present at the scene on the evening of Baine’s death and she is brought in for questioning. Insisting all she encountered at the home was a body, she tells Morse and Lewis that she saw Acum as she left, waiting in a car around the corner.

Acum is therefore brought in for questioning but, after a couple of pints to aid his thinking of course, Morse seems content to let him go. He does however insist on driving Acum back to Reading and, when Acum claims his wife isn’t home, Morse gladly accepts the invitation to wait for her.

Once inside Morse calls out for Valerie, and sure enough she emerges from upstairs, Morse having finally realised that he had already met Valerie when he had called at Acum’s house earlier on but did not initially recognise her as she was wearing a face pack at the time.

Valerie returns to find her mother in a verbal altercation with Phillipson and his wife. Phillipson claims he and Grace Craven were having an affair and were together the night Baines died and yet despite initially confirming this to Morse, Craven now insists he is lying and that their affair ended months ago.

Valerie corroborates this version of events, explaining that she saw Phillipson as she was leaving Baines’ house on the evening in question.

While Morse pursues another romantic line of inquiry in the form of Dr Jane Robson, he finds himself on hand at an Oxford college when one of its foreign summer students is murdered.

The Japanese man, Yukio Li, excused himself from dinner and is discovered in his room in a ritual pose with injuries to his hands and feet and a dagger in his chest. However Max insists the cuts were to hide the fact that he’d previously been bound and gagged and that the lack of blood suggested the man had been dead for some time.

After a cassette tape, in a jiffy bag addressed to Yukio and containing traces of cocaine, is found in the back of the coach, Robson confirms to Morse that he had been to the summer school previously and was a drug dealer.

When another member of staff supporting the summer school, Graham Daniels, is found dead, Morse begins to suspect a wider plot and that perhaps his presence at the college dinner was contrived to give alibis to those present.

As Morse’s suspicions grow, particularly towards Kurt Friedman, a german who another student claims is a ‘phoney’ and Sir Wilfred Mulryne, the don of the college, he is told to drop his investigation by Superintendent Dewar but this only strengthens Morse’s resolve to crack the case.

Through further pestering of Dr Robson, and some theorising of his own, Morse finally establishes the truth. The death, or at least the kidnap and torture, of Yukio Li was planned by Dr Robson and her brother, the man pretending to be Kurt Friedman, as revenge for the torture of their father in Japan during WWII at the hands of Yukio’s father. Mulryne had disclosed this family connection to Dr Robson previously.

But the plan went awry as the doppelgänger they used for the Japanese was overpowered by Yukio who in turn pretended to be the doppelgänger himself and escaped. The dead man initially found was therefore not Yukio Li after all.

Yukio then used the cover of his ‘death’ to exact revenge himself on those complicit in the plot against him, starting with Daniels and then Michael Robson/Kurt Friedman, who is found dead in the showers. On seeing this, Morse immediately realises that Dr Robson is next and rushes to her aid, only to find that someone has rescued her already by bashing Yukio's head in with a croquet mallet after he had attempted to strangle her.

Morse and Lewis are called to a pub outside Oxford where a young woman named Sylvia King has been found dead in the car park, seemingly run over but with scratches on her face that suggest an attack.

An envelope, containing what Morse identifies as a coded letter, is found in Sylvia’s purse that is addressed to her superior at work, Jennifer Coleby so inquiries begin at an Oxford assurance company. Morse quickly presumes the envelope contained wads of cash.

Meanwhile the man Sylvia was due to meet for a date on the fateful evening begins to spend money in an extravagant fashion. He soon stumbles into trouble and is brought into the station, admitting he did take the money after discovering Sylvia and even her necklace but, despite this confession, Morse is unconvinced he could have killed her and lets him go.

Instead, an elderly woman claims to have seen Sylvia get into a red car at a bus stop on the night in question, and after her memory is jogged, she even remembers the registration plate, which takes Morse and Lewis to the home of Mrs and Dr Crowther, the latter Morse has encountered already giving a lecture at an Oxford college.

So while Sylvia hitching a lift with Crowther is established, the connection between her and Jennifer Coleby isn’t until Max, who happens to be related to the Crowthers, tells Morse that Sylvia was due to attend physio at the hospital the following day.

The witness at the bus stop had reported that another person had been with Sylvia that night but didn’t get into the car. Instead Sylvia had departed with the words, “see you in the morning”. Morse and Lewis then realise that the mysterious other person at the bus stop was not a colleague of Sylvia’s but Jennifer Coleby’s lodger, Mary Widdowson, who works as a nurse at the hospital.

By this time Crowther has had a heart attack whilst disposing of evidence from his car and so the episode climaxes at the hospital with Widdowson confessing to Morse what had really gone on: She and Crowther were engaged in an affair but with his potential appointment to a senior post at the University, Crowther wanted to give her money for a holiday so she would be out of the picture for a while. Hence the wads of cash (and the coded message, ‘please take it’) in an envelope that was to get to her via Coleby, only for Sylvia King to intercept it.

When Sylvia was coincidentally picked up by Crowther at the bus stop, Mary Widdowson didn’t get in but instead followed them to see what would happen between them. When Sylvia gets out of the car, Mary confronts her and knocks her to the ground, only for Crowther to inadvertently run over her as he reverses out of the car park.

Morse and Lewis are sent to Hanbury House where an upper class family have apparently suffered a break in and the theft of a number of paintings.

Sir Julius Hanbury, however, is nowhere to be seen which is particularly unusual since he is vying to be the next Master of an Oxford college and the vote is tied.

Exploring the grounds of Hanbury House, Morse is shown into the family mausoleum and the battered body of Sir Julius is shockingly discovered.

Soon after, Roger Meadows, the boyfriend of the family’s au pair, Michelle, overturns his sports car driving away from the house. Lewis notices that his brakes had been cut.

Two murders then, or possibly one, as when Lady Hanbury is put under some pressure by Morse’s enquiries she claims that Sir Julius’ death was suicide, which she and the gardener, John McKendrick, made to look like murder to present a less shameful story to the watching world. The ‘theft’ was similarly part of their plan and the paintings are later recovered from their hiding place.

But Morse is not satisfied by this wafer thin confession and keeps snooping, particularly around the attic where there happens to be a photographic studio. Lewis’ keen eye realises that the pictures being produced, in the style of Sir Julius’ classical paintings, in fact feature Michelle. The prior suggestion that Sir Julius might have been blackmailed is now grounded in evidence.

Lady Handbury’s alibi for the night of Sir Julius’ death soon falls apart under Morse’s questioning when she claims to have witnessed Plácido Domingo featuring in Tosca in Covent Garden, while Morse knows this didn’t happen as he himself was present for the performance.

Caught in her lies she finally confesses that her affair with the McKendrick had been long term, that on confronting Sir Julius in his studio, and discovering what he had been up to, there had been a struggle, and that she had killed him in self-defence.

She then had McKendrick cut the brakes of Roger Meadows’ car in response to his threats to sell the story of Sir Julius, the au pair and the pornographic pictures to the tabloid press.

An old college roommate of Morse's, Anthony Donn, comes to Oxford for an annual cricket match, calls Morse after 20 years and wants to get together and talk. They eat chips on a bench, but Donn never gets round to saying what is on his mind, though he tells a zen story. Morse soon gets distracted by a case where three people are killed in a hate crime in the fire bombing of a radical bookshop. Donn then turns up dead in his college lodging. At first sight it looks as if he has electrocuted himself, but puzzlingly he had a gun in his luggage. His wife says he hated guns. Lewis postpones his leave to go undercover as a college porter and replaces Donn on the cricket team, the Clarets. One of the team members, Vince Cranston, resents this as he is not a gentleman. At the cricket match between the Clarets and the Hearties, organized by another former college friend of Morse's, Roly Marshall, Lewis acquits himself well, while Morse dozes. Meanwhile Lewis had seen Peter Foster searching Donn's room. Both Anthony Donn's widow, Kate, and Peter Foster's apparent wife, Philippa, appear attracted to Morse.

During the cricket match, Peter Foster is found murdered in the changing rooms, stabbed in the chest with a pair of scissors. Morse confronts Philippa Foster, who admits that she is a customs investigator and Peter is not her husband but her boss. Over the last two years, they have traced regular exports of cocaine and heroin that correspond with the Clarets' tours to the Low Countries. They had not told Morse as he might have been involved. She persuades Morse to permit this year's tour to continue. When the tour bus arrives at Dover, it is searched but nothing is found. Meanwhile Morse has tailed Kate Donn and seen her passionately kissing Vince Cranston. Morse realises that, contrary to E. M. Forster's advice to "only connect", he has to delink the two killings. He discovers cocaine hidden in the seat of the wheelchair used by Roly Marshall and deduces that Jamie Jasper, Marshall's nephew, killed Foster. Jasper worked in international finance and so had the opportunity to obtain drugs in the Far East. Morse then goes to the radio studio where Kate Donn is hosting her chat show and arrests her for murdering her husband. The motive is that she wanted to leave him for Vince, but he threatened to kill either Vince or himself (hence the gun). Morse suspected this because Vince had given Kate a book on zen with a florid dedication.