Two of the names mentioned most often in Howard Hawks’ “The Big Sleep” (1946) are Owen Taylor and Sean Regan. One is the chauffeur for the wealthy Sternwood family. The other is an Irishman hired by old Gen. Sternwood “to do his drinking for him.” Neither is ever seen alive; Regan has disappeared mysteriously before the movie begins, and Taylor’s body is hauled from the Pacific after his Packard runs off a pier. Were they murdered? And does it even matter, since there are five other murders in the film?

One of the best-known of all Hollywood anecdotes involves the movie’s confusing plot, based on the equally confusing novel by Raymond Chandler. Lauren Bacall recalls in her autobiography, “One day Bogie came on the set and said to Howard, ‘Who pushed Taylor off the pier?’ Everything stopped.” As A.M. Sperber and Eric Lax write in “Bogart,” “Hawks sent Chandler a telegram asking whether the Sternwood’s chauffeur, Owen Taylor, was murdered or a suicide. ‘Dammit I didn’t know either,’ ” Chandler recalled.

It is typical of this most puzzling of films that no one agrees even on why it is so puzzling. Yet that has never affected “The Big Sleep’s” enduring popularity, because the movie is about the process of a criminal investigation, not its results.

The process follows private eye Philip Marlowe (Humprey Bogart) as he finds his way through the jungle of gamblers, pornographers, killers and blackmailers who have attached themselves to the rich old general and his two randy daughters (Bacall and Vickers). Some bad guys get killed and others get arrested, and we don’t much care–because the real result is that Bogart and Lauren Bacall end up in each other’s arms. “The Big Sleep” is a lust story with a plot about a lot of other things.

In “The Big Sleep,” the relationship between Bogart and Bacall is problematical: Marlowe isn’t sure whether he trusts this cool, elegant charmer. The 1946 version commits to their romance, and adds among other scenes one of the most daring examples of double entendre in any movie up until that time. The new scene puts Bacall and Bogart in a nightclub, where they are only ostensibly talking about horse racing:

Bacall:“…speaking of horses, I like to play them myself. But I like to see them work out a little first. See if they’re front-runners or come from behind… I’d say you don’t like to be rated. You like to get out in front, open up a lead, take a little breather in the back stretch, and then come home free….”Bogart:“You’ve got a touch of class, but I don’t know how far you can go.”Bacall:“A lot depends on who’s in the saddle.”

What you sense here is the enjoyable sight of two people who are in love and enjoy toying with one another.

It is one of the great film noirs, a black-and-white symphony that exactly reproduces Chandler’s ability, on the page, to find a tone of voice that keeps its distance, and yet is wry and humorous and cares. Working from Chandler’s original words and adding spins of their own, the writers wrote one of the most quotable of screenplays: It’s unusual to find yourself laughing in a movie not because something is funny but because it’s so wickedly clever. (Marlowe on the “nymphy” kid sister: “She tried to sit in my lap while I was standing up.”) Unlike modern crime movies which are loaded with action, “The Big Sleep” is heavy with dialogue–the characters talk and talk, just like in the Chandler novels; it’s as if there’s a competition to see who has the most verbal style.

Bacall is adequate in most scenes, and splendid in others–but the scenes themselves didn’t give her the opportunities that the reshoot did. In scenes like the “racing” conversation she has the dry reserve, the private amusement, the way of sizing up a man and enjoying the competition, that became her trademark. It’s astonishing to realize she was 20, untrained as an actor, and by her own report scared to death.

Bogart himself made personal style into an art form. What else did he have? He wasn’t particularly handsome, he wore a rug, he wasn’t tall (“I try to be,” he tells Vickers), and he always seemed to act within a certain range. Yet no other movie actor is more likely to be remembered a century from now. And the fascinating subtext in “The Big Sleep” is that in Bacall he found his match.

You can see it in his eyes: Sure, he’s in love, but there’s something else, too. He was going through a messy breakup with his wife, Mayo, when they shot the picture. He was drinking so heavily he didn’t turn up some days, and Hawks had to shoot around him. He saw this coltish 20-year-old not only as his love but perhaps as his salvation. That’s the undercurrent. It may not have been fun to live through, but it creates a kind of joyous, desperate tension on the screen. And since the whole idea of film noir was to live through unspeakable experiences and keep your cool, this was the right screenplay for this time in his life.

Howard Hawks (1896-1977) is one of the great American directors of pure movies (“His Girl Friday,” “Bringing Up Baby,” “Red River,” “Rio Bravo”), and a hero of auteur critics because he found his own laconic values in many different kinds of genre material. He once defined a good movie as “three great scenes and no bad scenes.” Comparing the two versions of “The Big Sleep” reveals that the reshoots inserted one of the great scenes, and removed some of the bad ones, neatly proving his point.