I was flooded by too many choices as well. However, I finally decided to propose an old classic,
The Maltese Falcon, by Dashielle Hammett. It just sounds like fun.
The story itself needs no introduction, so just a bit of background but from
Wikipedia:
Sam Spade is a private detective in San Francisco, in partnership with Miles Archer. The beautiful "Miss Wonderley" hires them to follow Floyd Thursby, who has run off with her sister. Archer takes the first stint but is found shot dead that night. Thursby is also killed later and Spade is a suspect. The next morning, Spade coolly tells his office secretary, Effie Perine, to have the office door repainted to read simply "Samuel Spade".
"Miss Wonderley" is soon revealed to be an acquisitive adventuress named Brigid O'Shaughnessy, involved in the search for a black statuette of unknown but substantial value.
The Maltese Falcon is a 1930 detective novel by American writer Dashiell Hammett, originally serialized in the magazine Black Mask beginning with the September 1929 issue. The story is told entirely in external third-person narrative; there is no description whatever of any character's internal thoughts or feelings, only what they say and do, and how they look. The novel has been adapted several times for the cinema.
The main character, Sam Spade (who also appeared later in some lesser-known short stories), was a departure from Hammett's nameless detective, The Continental Op. Spade combined several features of previous detectives, notably his cold detachment, keen eye for detail, unflinching, sometimes ruthless, determination to achieve his own form of justice, and a complete lack of sentimentality.
Although Hammett himself worked for a time as a private detective for the Pinkerton Detective Agency in San Francisco (and used his given name, Samuel, for the story's protagonist), Hammett asserted that "Spade has no original. He is a dream man in the sense that he is what most of the private detectives I worked with would like to have been, and, in their cockier moments, thought they approached."
Overdrive: as best I can tell, it appears to be available though not at my library.
Kindle $2.99 US; $0.99 CA
Kobo $0.99 CA; $9.99 US; $12.99 AUD
Sorry - it seems to be quite a bit more expensive in via Kobo.