Nothing much happens for the first two-thirds of "Only If You're Lucky" and theneverythinghappensallatonce.

With "A Flicker in the Dark" and, especially, "All the Dangerous Things," Stacy Willingham established herself as America's answer to Alice Feeney: a writer whose plotting is deft enough to guide us through several shocking twists per book without making us throw it across the room in disbelief.

She still has that going for her in "Only If You're Lucky," but the plotting skill that kept the surprises coming in her first two books has (temporarily, I hope) vanished. Willingham makes the mistake of thinking we're interested in the thought processes of heroine Margot (we aren't — she's a blank) and that we've bought into the dual mysteries of the disappearance of one of her college roommates, Lucy, and the apparent murder of a frenemy.

It's a serviceable story, albeit one vaguely reminiscent of Donna Tartt's far superior "The Secret History." But we know the territory early in "Only If You're Lucky" and it takes too long for Willingham, who has cranked out three books in as many years, to begin introducing unexpected developments. Once she does, it feels like the switcheroos come almost every other page.

By that point, it's too late. Willingham seems to know it, too. She tries to obscure the lack of surprises by juggling multiple timelines, one before and one after Lucy's disappearance. But Margot and her shiftless roommates change so little over the course of the novel that the before-and-after stuff doesn't accomplish what Willingham likely hopes. In fact, there's a sense that she's as annoyed by her young characters — who never seem to go to class or meet to lay out the yearbook — as we are.

That could be the issue. Willingham's previous books focused on protagonists around her age (32), vividly capturing their senses of humor and behavioral inconsistencies. The characters in "Only If You're Lucky" don't emerge in that way, possibly because their creator has outgrown them.

Only If You're Lucky

By: Stacy Willingham.

Publisher: Minotaur, 370 pages, $26.