A beautiful young woman, Brigid O'Shaunessy (Mary Astor) contacts a detective agency to find her runaway sister. Miles Archer takes the case, but when he gets gunned down, his partner Sam Spade (Humphrey Bogart) resolves to solve the case and catch Miles' murderer. One thing leads to another, and Sam Spade meets Joel Cairo (Peter Lorre), Guttman the Fat Man, (Sydney Greenstreet) and his gunsel Wilbur (Elisha Cook Jr), finds out there is no sister, but that everybody is actually interested in a mysterious black bird, the Maltese Falcon, said to be a gold bird covered with precious stones. During all this, Floyd Thursby, a pal of Birgid's is killed, as is Captain Jacobi (Walter Huston), another friend of Brigid's. At the very end, Sam Spade must decide if he'll throw his lot in with Brigid or do the right thing by his dead partner.