The Big Sleep (1946)
Of the mainstream Hollywood noirs few were finer than this Howard Hawks-helmed Bogart and Bacall innuendo-fest, where Philip Marlowe is hired to protect the wealthy and deeply fucked-up Sternwoods from a myriad scandals. No one bothers to follow the famously convoluted plot. Rather it's the terrifically clever dialogue and variously unsubtle hints at devious behaviour that drive each scene. William Faulkner is credited as scriptwriter, though all the best exchanges are directly lifted from Raymond Chandler's novel (which is well worth reading not only for its literary merit but if you're ever curious to figure out who exactly kills whom and to what purpose).
dir: Howard Hawks
wr: William Faulkner
cast: Humphrey Bogart, Lauren Bacall, John Ridgely, Martha Vickers, Louis Jean Heydt, Elisha Cook Jr., Charles Waldron, Regis Toomey, Sonia Darin, Bob Steele, Tom Rafferty, Dorothy Malone