In Emma Cline's "The Guest," 22-year-old Alex lies, trespasses, manipulates and steals over the course of a summer week in a wealthy oceanside enclave.

Originally the guest of Simon — a man more than twice her age — Alex loses his favor (and a place in his house) when she swims, fully clothed, with someone else's husband. As Simon dismisses her, Alex recalls how quickly she adapted to her new lifestyle: "She thought of the bed she had left that morning — she had gotten used to the fact of the bed. Now it was disintegrating." In an act of willful delusion, Alex imagines that Simon will still want to see her at his Labor Day party, and that the immediate task is to figure out "how to burn the next six days."

Cline, whose previous book was a fictionalized take on "The Girls" in Charles Manson's orbit, writes prose that is clear, steady and restrained, surveying the pleasures and idiosyncrasies of extreme wealth with cool specificity. The novel adds pressure to the day-burning questionby giving Alex a dangerous person to avoid: Dom, from whom she has stolen, and who sends her increasingly threatening text messages.

Alex's profession, presented through occasional allusions and Cline's meticulous diction, involves careful attention to her body: "Alex considered breast augmentation. She rewrote her ad copy, paid an exorbitant fee to be featured in the first page of results. Dropped her rates, then dropped them again." When she meets Simon, "she would have clocked the man immediately as a civilian, someone whose self-conception wouldn't include participation in certain arrangements." Cline writes that Alex had "been overlooking the protection a civilian could offer." That need for protection, and the subtext of battle or war, continues to grow as Alex waits for Labor Day.

Alex's circumstances are sorrowful, but Cline still manages to find humor, particularly in the way Alex, unimpressed, sums up the people she deceives — and there are many. Sometimes there is cruelty in her calculations — the desperation of Margaret, whom she meets at a club, is so unappealing that Alex turns down her offer of shelter — but it is also clear that Alex is perceptive and intelligent.

Her resourcefulness does not contradict a desire to be rescued, however. Swimming alone in the ocean, she finds herself farther from shore than she'd meant to go. "Surely," Cline writes, "if Alex had been in any real danger … one of these people would have stepped in to help."

As Alex's reckless decisions bring her closer and closer to peril, Cline maintains this intriguing balance of detached certainty and growing fear.

Jackie Thomas-Kennedy's writing has appeared in American Short Fiction and One Story. She is a former Stegner Fellow at Stanford University.

The Guest
By: Emma Cline.
Publisher: Random House, 291 pages, $28.