Backfire by Dan Marlowe

Marty Donovan is a cop who happens to be in love with Lenore, his partner's wife. When the two cops can't crack a tough case, Lenore suggests a stakeout that's not approved by the department. Her husband is killed, and Marty begins a complicated cover-up as he tries to find the killer.

A Study in Scarlet by Arthur Conan Doyle

A Study in Scarlet is an 1887 detective novel by British author Arthur Conan Doyle. Written in 1886, the story marks the first appearance of Sherlock Holmes and Dr. Watson, who would become the most famous detective duo in popular fiction. The book's title derives from a speech given by Holmes, a consulting detective, to his friend and chronicler Watson on the nature of his work, in which he describes the story's murder investigation as his "study in scarlet": "There's the scarlet thread of murder running through the colorless skein of life, and our duty is to unravel it, and isolate it, and expose every inch of it."

The story, and its main characters, attracted little public interest when it first appeared. Only 11 complete copies of the magazine in which the story first appeared, Beeton's Christmas Annual for 1887, are known to exist now and they have considerable value. Although Conan Doyle wrote 56 short stories featuring Holmes, A Study in Scarlet is one of only four full-length novels in the original canon. The novel was followed by The Sign of the Four, published in 1890. A Study in Scarlet was the first work of detective fiction to incorporate the magnifying glass as an investigative tool.

The Red Thumb Mark by R. Austin Freeman

Richard Austin Freeman (11 April 1862 London - 28 September 1943 Gravesend) — known as R. Austin Freeman — was a British writer of detective stories, mostly featuring the medico-legal forensic investigator Dr Thorndyke. He claimed to have invented the inverted detective story (a crime fiction in which the commission of the crime is described at the beginning, usually including the identity of the perpetrator, with the story then describing the detective's attempt to solve the mystery) and used some of his early experiences as a colonial surgeon in his novels. A large proportion of the Dr Thorndyke stories involve genuine, but often quite arcane, points of scientific knowledge, from areas such as tropical medicine, metallurgy and toxicology.

The Circular Staircase by Mary Roberts Rinehart

The Circular Staircase is a mystery novel by American writer Mary Roberts Rinehart. The story follows dowager Rachel Innes as she thwarts a series of strange crimes at a summer house she has rented with her niece and nephew. The novel was Rinehart's first bestseller and established her as one of the era's most popular writers. The story was serialized in All-Story for five issues starting with the November 1907 issue, then published in book form by Bobbs-Merrill in 1908.

Rinehart was inspired to write the novel after a visit to Melrose, a Gothic Revival castle in Northern Virginia.

The Circular Staircase pioneered what became known as the "had I but known" school of mystery writing, which often feature female protagonists and narrators who foreshadow impending danger and plot developments by reflecting on what they might have done differently. Rinehart employed this formula in many of her later works, and it inspired dozens of subsequent stories. The novel was adapted for the screen twice: as a silent film in 1915, and for the television series Climax! in 1956. Its best known adaptation was as the play The Bat, which became a major Broadway hit and inspired a number of later works, including several adaptations of its own.

Rachel Innes is a spinster who has had custody of her orphaned niece and nephew since they were children. Halsey and Gertrude are now 20 and 24, respectively, and they talk Rachel into renting a house in the country for the summer.

The first night Rachel is there, there is a mysterious trespasser and something falls down the stairs in the middle of the night. The second night, after Halsey and Gertrude have arrived, there is a murder, and Halsey and the friend he has brought to stay disappear.

Halsey returns a few days later, without his friend and without an explanation, but by then many other developments have occurred, to the chagrin of the residents.

The Daffodil Mystery by Edgar Wallace

Mr. Thornton Lyne, minor poet and head of Lyne's Stores, was found dead in Hyde Park, murdered undoubtedly! The clues were numerous but contradictory...

When Mr. Thomas Lyne, poet, poseur. and owner of Lyne's Emporium insults a cashier, Odette Rider, she resigns. Having summoned detective Jack Tarling to investigate another employee, Mr. Milburgh, Lyne now changes his plans. Tarling and his Chinese companion refuse to become involved. They pay a visit to Odette's flat. In the hall, Tarling meets Sam, convicted felon and protégé of Lyne. Next morning Tarling discovers a body. The hands are crossed on the breast, adorned with a handful of daffodils.

Arsene Lupin vs Herlcok Sholmes by Maurice Leblanc

Arsene Lupin vs Herlock Sholmes. A very thinly disguised Sherlock Holmes takes on Arsene Lupin in solving a mystery.