Alfred Hitchcock and the Three Investigators in... (from book 31, The Three Investigators in...)
- The Secret of Terror Castle (1964, by Robert Arthur)[1]
- The Mystery of the Stuttering Parrot (1964, by Robert Arthur)[2]
- The Mystery of the Whispering Mummy (1965, by Robert Arthur)[3]
- The Mystery of the Green Ghost (1965, by Robert Arthur)[4]
- The Mystery of the Vanishing Treasure (1966, by Robert Arthur)[5]
- The Secret of Skeleton Island (1966, by Robert Arthur)[6]
- The Mystery of the Fiery Eye (1967, by Robert Arthur)[7]
- The Mystery of the Silver Spider (1967, by Robert Arthur)[8]
- The Mystery of the Screaming Clock (1968, by Robert Arthur)[9]
- The Mystery of the Moaning Cave (1968, by William Arden)[10]
- The Mystery of the Talking Skull (1969, by Robert Arthur)[11]
- The Mystery of the Laughing Shadow (1969, by William Arden)[12]
- The Secret of the Crooked Cat (1970, by William Arden)[13]
- The Mystery of the Coughing Dragon (1970, by Nick West)[14]
- The Mystery of the Flaming Footprints (1971, by M. V. Carey)[15]
- The Mystery of the Nervous Lion (1971, by Nick West)[16]
- The Mystery of the Singing Serpent (1972, by M. V. Carey)[17]
- The Mystery of the Shrinking House (1972, by William Arden)[18]
- The Secret of Phantom Lake (1973, by William Arden)[19]
- The Mystery of Monster Mountain (1973, by M. V. Carey)[20]
- The Secret of the Haunted Mirror (1974, by M. V. Carey)[21]
- The Mystery of the Dead Man's Riddle (1974, by William Arden)[22]
- The Mystery of the Invisible Dog (1975, by M. V. Carey)[23]
- The Mystery of Death Trap Mine (1976, by M. V. Carey)[24]
- The Mystery of the Dancing Devil (1976, by William Arden)[25]
- The Mystery of the Headless Horse (1977, by William Arden)[26]
- The Mystery of the Magic Circle (1978, by M. V. Carey)[27]
- The Mystery of the Deadly Double (1978, by William Arden)[28]
- The Mystery of the Sinister Scarecrow (1979, by M. V. Carey)[29]
- The Secret of Shark Reef (1979, by William Arden)[30]
- The Mystery of the Scar-Faced Beggar (1981, by M. V. Carey)[31]
- The Mystery of the Blazing Cliffs (1981, by M. V. Carey)[32]
- The Mystery of the Purple Pirate (1982, by William Arden)[33]
- The Mystery of the Wandering Cave Man (1982, by M. V. Carey)[34]
- The Mystery of the Kidnapped Whale (1983, by Marc Brandel)[35]
- The Mystery of the Missing Mermaid (1983, by M. V. Carey)[36]
- The Mystery of the Two-Toed Pigeon (1984, by Marc Brandel)[37]
- The Mystery of the Smashing Glass (1984, by William Arden)[38]
- The Mystery of the Trail of Terror (1984, by M. V. Carey)[39]
- The Mystery of the Rogues' Reunion (1985, by Marc Brandel)[40]
- The Mystery of the Creep-Show Crooks (1985, by M. V. Carey)[41]
- The Mystery of Wrecker's Rock (1986, by William Arden)[42]
- The Mystery of the Cranky Collector (1987, by M. V. Carey)[43]
- The Mystery of the Ghost Train (published in German only in 2024,[44] by M. V. Carey; unfinished/unpublished when the original series was cancelled)