Plot
As kids, Darryl and Kevin Walker grew up as fans of the television series Batman. Now grown, Darryl is a clumsy, nerdy repairman, while his brother Kevin is a tabloid news cameraman. They both live with their grandmother, who is an avid supporter of Alderman Marvin Harris, a politician from their neighborhood running for mayor on an anti-corruption platform. Kevin is interested in getting out of making tabloids and doing a serious story about mobster Michael "The Suit" Minelli, but his attempts to do so are shot down by his boss, Larry Stone, a perverted tabloid news junkie. Darryl is overly optimistic and almost childishly naive to the harsh realities of living in the inner city (such as the crackhouse next door), but is a brilliant inventor, having constructed a mobile robot assistant named J-5, among other creations.
One night, after Harris wins acclaim by publicly refusing a bribe from Minelli, Grandma Walker is murdered by the mobster's henchmen at Harris's campaign headquarters. The murder opens Darryl's eyes to the urban decay around him and he begins to fight crime by boldly saving an elderly transit passenger from being mugged, but overreaches by storming the crackhouse next door to rebuke the gang members. He then decides to become a vigilante superhero, using his technical expertise to create weapons and gadgets in particular, a substance which renders ordinary clothing bulletproof for his crime-fighting crusade, all to the annoyance of Kevin.
After Darryl is nearly killed trying to protect a citizen on the street and is arrested by the cops who ridiculed him after he demanded to see the police commissioner, Kevin takes Darryl to see a psychiatrist. It doesn't work in Kevin's favor, as Darryl denies being a superhero and puts the blame on Kevin, whom the psychiatrist then attempts to psychoanalyze. Kevin changes his mind and goes along with the fantasy, believing that it's Darryl's way to cope with the murder of their grandmother, but under the guidance of starting a neighborhood watch instead. When a girl tells them of a pregnant woman trapped in an elevator, Darryl arrives as his superhero alter-ego. Upon delivering the baby, he is surrounded by many, including reporters. Asking for his name, Darryl just stares Kevin says he's gone blank, which everyone interprets as his name: Blankman.
Over time, Darryl uses his Blankman identity to protect various community members, build up a reputation, and inspire not only the town's citizens but other real-life superheroes. One person interested in him is Kimberly Jonz, a fellow reporter whom Kevin hopes to win the affection of. When Kimberly wants to know if it's possible to get an interview with Blankman, Kevin begs Darryl to allow her to interview him. He relents, on the condition that she wear a carnation. Taking her on his Blank-Cycle at the train tracks, he brings her to his secret hideout: the "Blank Station," an abandoned subway station filled with all of his inventions, or, in his words, "junk." Kimberly interviews him about how and why he took up crime fighting, revealing it was because of the death of his grandmother. Impressed by his heroics and modesty, Kimberly immediately falls in love with him. She kisses him, only for him to panic when he gets an erection.
Mayor Harris attempts to bring in outside money to pay the IOUs the city has been giving its workers and requests that Blankman be there to protect the people and receive a special award. As the money is released, Minelli's henchmen storm the bank and take the mayor hostage, threatening to detonate explosives. At the police chief's request and the crowd's chants, Blankman attempts to save the mayor, and even with Kevin's help, he is unable to stop the crooks, nor defuse the bombs. Before the bombs go off, Darryl reveals his identity and his grandmother's support for the mayor. Harris wishes him well, warning him to run, and says he will tell his grandmother about Darryl. Blankman runs out screaming as the bank explodes, killing Harris. The crowd, seeing his failure, turn on him and chase him down the street. Now a pariah, Darryl gives up on crime fighting and even a possible relationship with Kimberly. Trying for a normal life, he gets a job at a McDonald's.
Wanting a great story, Larry Stone manages to contact Minelli and trades knowledge of Blankman's love for Kimberly in exchange for an exclusive interview. While researching Minelli and Grandma Walker's murder, Kimberly realizes his true identity and calls Kevin with the news, only for Minelli to take Kimberly hostage. Thinking he is talking to Blankman, Minelli threatens to kill Kimberly if Blankman doesn't show up. Kevin rushes to Darryl's workplace with the news, but Darryl refuses to help until Kevin reveals Minelli killed their grandmother. They leave and change to their superhero identities: Blankman, and Kevin agreeing to wear a costume himself as "Other Guy." The two heroes rush to the TV station, where Minelli has murdered a reporter and is threatening others, including Stone. The two engage in a fight with Minelli's goons, but they lose. They are placed in a water tank and left to drown, with Stone and Kimberly chained up and left to die, and Minelli has hidden bombs to destroy the building. Blankman calls J-5 to save them and succeeds. The duo then finds the bombs in the women's bathroom, and stuffs the explosives inside J-5, while he frees Kimberly (Stone is left behind, as a joke by Other Guy). Once outside, the explosives detonate, destroying J-5. Distraught, Blankman swears revenge.
Tracking Minelli to his factory hideout, Blankman and Other Guy prepare for the final battle. Other Guy is overconfident and gets wounded because his costume is not bulletproof. Blankman then defeats Minelli's goons with his electric "newchucks," and activates his jet-powered roller blades to capture Minelli, delivering him to the police and finally avenging their grandmother's death. Blankman, this time with Other Guy, is once again acknowledged as a hero by the people and receives the Mayor Harris Award for outstanding community service at a ceremony in their honor, while Other Guy receives a Blankman T-shirt, much to his disgust. After the ceremony, Kevin introduces Kimberly to Darryl. The two make light conversation until Kimberly pretends to see a purse snatcher, which puts Darryl on high alert. It was a trick, as Kimberly reveals she already knows that Darryl is Blankman to prove it, she kisses Darryl, causing him to fall to the ground embarrassingly like before. The film ends with a shot of a banner that reads "We Love You Blankman and Other Guy."
