The main difference in the two prints of The Big Sleep -- the distillation of 20 minutes' worth of refurbished footage -- is in the treatment of Lauren Bacall, who plays opposite Bogart. Robert Gitt, the UCLA preservationist who takes us through the changes in a postscript to the 1945 version, explains that Bacall's young career, blossoming when she debuted opposite Bogart in Hawks's To Have and Have Not in 1944, stalled when she got lousy reviews in her second feature, Confidential Agent. The Big Sleep was already completed and awaiting release at Warner Bros.; Bacall's masterful agent, Charles K. Feldman, persuaded Jack Warner that if he retook one of Bacall's scenes and pumped up her role, he'd have a new star. Warner complied (taking full credit for the idea). Gitt points out the excision of the scene Feldman hated, where Bacall (playing Vivian Sternwood, the older of two sisters with "corrupt blood") appears at Marlowe's office with her face flattened by a horrid veil. The crucial plot material was transferred to a restaurant scene that Bacall enters in a stunning satiny vest -- though that scene is more famous as the tête-à-tête in which she and Bogart exchange double entendres about horse racing.

Gitt also juxtaposes two versions of the penultimate scene, where Marlowe, having been knocked out by a creep named Canino (cowboy star Bob Steele), comes to with his hands tied and finds both Vivian and the long-absent wife of shady gambling house owner Eddie Mars (John Ridgely) dancing attendance on him. (In the novel, it's Mona Mars, not Vivian, he falls for.) Gitt draws your attention to the way the staging and camera angles in the later version favor Bacall, and he mentions that the original Mrs. Mars, Patricia Clarke, was replaced by Peggy Knudsen. He doesn't guess the reason, though we can. Clarke is elegant and a Lauren Bacall look-alike, whereas Knudsen (sporting a chintzier outfit) has a wide '40s-cutie face like Virginia Mayo's.

The version Warners released plays a little better: it feels quicker. (In fact, they're the same length.) And though Bacall is terrific in both, you're happy to have more of her in the '46 version -- who would want to live without the horse-racing banter? But it's fun to see the first version and play movie detective, especially if you know the film well, and in either form it's a sensationally enjoyable picture. Bogart may have been still better in The Maltese Falcon and The Treasure of the Sierra Madre, but his line readings here are as witty and self-delighted as any he ever gave. And what lines he gets to read! The screenwriting is seamless: without consulting the novel, there's no way to guess where Chandler ended and the adapters (Jules Furthman, Leigh Brackett, and William Faulkner) began. The atmosphere is perfumed and baroque; Hawks manages to suggest the sexual preference of the first victim, Arthur Geiger, without breaking the Hays Code rules. (Chandler isn't so coy.) And the supporting cast is supremely memorable, from Martha Vickers as Vivian's thumb-sucking sister Carmen, carelessly blowing wisps of hair off her forehead as a corpse leers up at her, to Dorothy Malone as a randy bookstore clerk and compact Elisha Cook Jr. and leggy, languid-faced Sonia Darrin as the unlikeliest of couples. (They're never actually on screen together.) Seeing what Hawks stored in the can before Charles K. Feldman went to work for his client simply extends the fun.