Books about Mystery and detective stories (sorted alphabetically)
- Moving Picture Boys on the Coast Victor Appleton
- Mrs Peixada Henry Harland
- Mystery at Camp Lenape Carl Saxon
- Mystery Hunters at the Haunted Lodge Capwell Wyckoff
- Mystery of Jockey Hollow Cleo F. Garis
- Mystery Wings Roy J. Snell
- Nancy Brandon's Mystery Lilian Garis
- Nine of Hearts: A Novel B. L. Farjeon
- Oakdale Boys in Camp Morgan Scott
- Oliver Bright's Search; or, The Mystery of a Mine Edward Stratemeyer
- Orchard Secret Cleo F. Garis
- Outdoor Girls Around the Campfire; or, The Old Maid of the Mountains Laura Lee Hope
- Outdoor Girls at Ocean View; Or, The Box That Was Found in the Sand Laura Lee Hope
- Peggy Finds the Theatre Virginia Hughes
- Peggy Plays Off-Broadway Virginia Hughes
- Penny Allen and the Mystery of the Hidden Treasure Jean L. McKechnie
- Phantom Friend Margaret Sutton
- Phantom Town Mystery Carol Norton
- Phantom Treasure Harriet Pyne Grove
- phantom violin : a mystery story for girls Roy J. Snell
- Phantom Yacht Carol Norton
- Phoebe Daring: A Story for Young Folk L. Frank Baum
- Pirate Shark Elliott Whitney
- Purple Flame Roy J. Snell
- Putnam Hall Champions; or, Bound to Win Out Edward Stratemeyer