- M Is for Marquess
- M. or N. "Similia Similibus Curantur"
- Madam Sibyl's First Client: A Victorian San Francisco Story
- Madam Storey, Private Investigator
- Madam, Will You Talk?
- Madame de Sévigné
- Madame Gestapo, il Serial
- Madame Koska & le Spectre de la Rose
- Madame Midas
- Maddening Minx
- Madeiragrab
- Madeiraschweigen
- Madman's Dance
- Madness
- Maggie
- Maggie Sullivan Mysteries Books 1-4
- Maggie Sullivan Mysteries Books 5-7
- Magic and Mystery
- Magpie Murders
- Mai-Schnee
- Maiden Lane
- Maiden Weeping, A
- Mail Order Bride - A Bride for Aaron
- Mail Order Bride - Ellen’s Conflict
- Mail Order Bride - Faith Creek Brides - Books 1-10
- Mail Order Bride - Frances's Destiny
- Mail Order Bride - Georgina's Destiny
- Mail Order Bride - Maddy's Destiny
- Mail Order Bride - Maeve's Destiny
- Mail Order Bride - Mayme's Destiny
- Mail Order Bride 4 Book Box Set
- Mail Order Bride Amelia
- Malheur: A Balkan War Mystery
- Malice Aforethought
- Mambo to Murder
- Mammon - Für deine Sünden sollst du büßen & Phoenix - Unsere Rache wird euch treffen
- MAMMON - Für Deine Sünden wirst Du büßen
- Mamur Zapt and the Return of the Carpet
- Man and Wife
- Man mördar inte en överlärare
- Man's Place in the Universe
- Manners and Monsters
- Manners and Monsters Collection
- Manor of Death, The
- The Mansions of Murder
- Manual para damas sobre el cotilleo y el asesinato
- Manual para damas sobre el protocolo y el asesinato
- Manzoni e la spia austriaca
- Manželské zrcadlo
- Mara's Legacy
- Marcapasos
- March Violets
- Marché noir
- Margaret Dashwood's Diary
- Marie-Antoinette : Vienne, la jeunesse d'une reine
- Marion Lane and the Midnight Murder
- Marion Lindström
- Marley Was Dead: A Christmas Carol Mystery
- Marlowe und die Geliebte von Lope de Vega: Roman
- Marquette Island, View from the Snows
- Marquise von Pompadour
- Married by Moonlight
- Married on a Wicked Morning
- Marry-Go-Round
- Martin Hewitt, Investigator
- Marvatten
- Mary Clockwork
- Mary Ferrera spielt System
- Mary MacDougall Mysteries Box Set
- Maschine
- Mask of Silver
- Masked Rider: Origins
- Masks, Mayhem and Murder
- Masquerade at Middlecrest Abbey
- Master Of Pamor
- Master of Souls
- Mathew's Tale
- Mathilde
- Matin blême à Rosporden
- Matin de cendre
- Matter of Breeding, A
- Maverick Jack: An Out of Time Novel
- Maximum Moxie
- Mayaguez and the Murder Ship: Two Tales of Maritime Heroism
- Mayas, El Ciclo Desconocido: El Enigma de la Pirámide
- Mayhem in the Library
- Media luna
- Mediatores
- Medical Adventures of Sherlock Holmes, Dr. Watson, and Dr. Verner
- Medieval to Modern: An Anthology of Historical Mystery Stories
- Mefistofele
- Meister Frantz auf Geisterjagd
- Memoirs from Mrs. Hudson's Kitchen
- Memory Book
- Memory of Flames
- Memory's Hostage
- Men Like Us
- Menorah
- Mephisto Waltz
- Merchants of Menace
- Mercurium
- Mercy Me