Marlowe lives in the corrupt, crime-ridden streets of the City of Angels, and he's hired by General Sternwood to dig up information on a blackmailer named Geiger. Usually when we think of stories featuring a quest, books like the Odyssey or The Lord of the Rings come immediately to mind. Chandler's Big Sleep definitely isn't what we would typically describe as a quintessential quest tale.
But even though there's no life-affirming ending, Marlowe does have to go through numerous trials to reach his end goal. And there are many key elements that make this novel what we'd see as a modernized quest story. For one thing, Marlowe's a bit of a modern-day knight. Plus, Marlowe's search for clues can be described as a quest for knowledge as he tries to find all the pieces to solve the puzzle.
As Marlowe proceeds to follow up on every lead that comes his way, he has to face many life-threatening situations. He's placed at gunpoint when he confronts Joe Brody about his scheme to blackmail Vivian. He has to resist many temptations, most of which come from Carmen, who flirts with him constantly.
Even though there are too many twists and turns in The Big Sleep to list all the stages of Marlowe's journey, notice how Marlowe's goals change as the novel progresses. His initial goal is only to track down Geiger, but after he is killed, Marlowe's journey develops into a search for Joe Brody, which then leads him to Eddie Mars.
In all of this, Marlowe is also trying to find out information about the General's son-in-law, Rusty Regan, who has disappeared without a trace. Suffice it to say, the more Marlowe becomes involved in the lives of the Sternwood family, the greater the dangers that he faces.
Marlowe has finally discovered a lead that takes him straight to the hideout of Mona Grant, who had apparently run off with Regan. But when Marlowe finds her, he learns that she had never left with Regan.
Marlowe seems to have finally reached his goal when he is able to speak face to face with Mona and ask her where Regan is. But upon learning that she never ran off with Regan, Marlowe's forced to go back to square one. No one seems to know the whereabouts of Regan, or else they're all hiding it from Marlowe. Poor guy, he just can't seem to catch a break.
Marlowe goes to tell General Sternwood that he's off the case. As he's leaving the Sternwood mansion, he runs into Carmen, who asks him to teach her how to shoot. But when Marlowe's back is turned, Carmen fires at him. Luckily, the gun is loaded with blanks.
Marlowe's final showdown with Carmen may not be as life-threatening as his previous experiences of being held up at gunpoint, but Marlowe definitely wins points for outwitting the femme fatale. Putting blanks into her gun was a stroke of genius and it allowed him to finally tie together all the loose ends of the Sternwood family history.
Marlowe tells Vivian he knows the secret that she's been trying to cover up, and he gives her three days to put Carmen into a mental institution and to leave town.
Marlowe has finally solved the case, but he leaves the Sternwood residence feeling pretty down in the dumps. Unlike a typical quest tale where the hero returns home with a more positive outlook on the future, Marlowe knows that he's now a part of the corruption behind Rusty's death and the novel ends on a dark note with Marlowe feeling disillusioned.