Private Investigator Philip Marlowe is hired by wealthy General Sternwood regarding a matter involving his youngest daughter Carmen. Before the complex case is over, Marlowe sees murder, blackmail, deception, and what might be love.

Burglar Nat Harbin (Dan Duryea) and his two associates set their sights on wealthy spiritualist Sister Sarah, who has inherited a fortune — including a renowned emerald necklace — from a Philadelphia financier. Using Nat’s female ward, Gladden (Jayne Mansfield), to pose as an admirer and case the mansion where the woman lives, they set up a perfect break-in. Things get complicated afterwards.