Books about Mystery and detective stories (sorted alphabetically)
- Putnam Hall Encampment; or, The Secret of the Old Mill Edward Stratemeyer
- Puzzle in the Pond Margaret Sutton
- Queen's Error Henry Curties
- Radio Girls at Forest Lodge; or, The Strange Hut in the Swamp Margaret Penrose
- Radio Girls on Station Island: The wireless from the steam yacht Margaret Penrose
- Ralph, the Train Dispatcher; Or, The Mystery of the Pay Car Allen Chapman
- Rambler Club on the Texas border W. Crispin Sheppard
- Rambler Club's house-boat W. Crispin Sheppard
- Rambler Club's motor car W. Crispin Sheppard
- Red Dynamite Roy J. Snell
- Red Rat's Daughter Guy Boothby
- Revenge! Robert Barr
- Riddle of the Storm Roy J. Snell
- Rope of Gold Roy J. Snell
- Ruth Fielding At College; or, The Missing Examination Papers Alice B. Emerson
- Ruth Fielding at Snow Camp; Or, Lost in the Backwoods Alice B. Emerson
- Ruth Fielding Down East; Or, The Hermit of Beach Plum Point Alice B. Emerson
- Ruth Fielding in the Great Northwest; Or, The Indian Girl Star of the Movies Alice B. Emerson
- Ruth Fielding In the Saddle; Or, College Girls in the Land of Gold Alice B. Emerson
- Ruth Fielding of the Red Mill; Or, Jasper Parloe's Secret Alice B. Emerson
- Ruth Fielding on the St. Lawrence; Or, The Queer Old Man of the Thousand Islands Alice B. Emerson
- Saboteurs on the River Mildred A. Wirt
- scarabée d'or (French) Edgar Allan Poe
- Scientific Sprague Francis Lynde
- Secret of Steeple Rocks Harriet Pyne Grove