Books about Mystery and detective stories (sorted alphabetically)
- Mary Louise and the Liberty Girls L. Frank Baum
- Mary Louise at Dorfield Emma Speed Sampson
- Mary Louise in the Country L. Frank Baum
- Mary Louise Stands the Test Emma Speed Sampson
- McAllister and His Double Arthur Cheney Train
- Meadow-Brook Girls by the Sea; Or, The Loss of The Lonesome Bar Janet Aldridge
- Mercer Boys at Woodcrest Capwell Wyckoff
- Mercer Boys' Cruise in the Lassie Capwell Wyckoff
- Missing at Marshlands Cleo F. Garis
- missing chums Franklin W. Dixon
- Missing Formula Mildred A. Wirt
- Missing Tin Box; Or, The Stolen Railroad Bonds Edward Stratemeyer
- Motor Boys Across the Plains; or, The Hermit of Lost Lake Clarence Young
- Motor Boys Afloat; or, The Stirring Cruise of the Dartaway Clarence Young
- Motor Boys After a Fortune; or, The Hut on Snake Island Clarence Young
- Motor Boys on a Ranch; or, Ned, Bob and Jerry Among the Cowboys Clarence Young
- Motor Boys on Road and River; Or, Racing To Save a Life Clarence Young
- Motor Boys on the Pacific; Or, the Young Derelict Hunters Clarence Young
- Motor Boys on the Wing; Or, Seeking the Airship Treasure Clarence Young
- Motor Boys on Thunder Mountain; Or, The Treasure Chest of Blue Rock Clarence Young
- Motor Boys Over the Rockies; Or, A Mystery of the Air Clarence Young
- Motor Girls at Camp Surprise; Or, The Cave in the Mountains Margaret Penrose
- Motor Girls in the Mountains; or, The Gypsy Girl's Secret Margaret Penrose
- Motor Rangers' Cloud Cruiser John Henry Goldfrap
- Motor Rangers Through the Sierras John Henry Goldfrap