Janie Johnson is a cheerfully ordinary 15-year-old whose world starts to unravel one day in the high school cafeteria. Idly glancing at a milk-carton photograph of a missing child, she sees her own face over the caption: ”Kidnapped.”

It doesn’t make sense. Janie knows that she wasn’t kidnapped when she was three, as the milk carton claims. She knows — or does she? — that her loving, decent parents are not kidnappers. But she can’t shake off the mystery because she remembers the dress in the photograph.

Caroline Cooney writes in the familiar, simple style of most young-adult novels, but The Face on the Milk Carton has an urgency that far transcends this often banal genre. It’s a gripper. You can’t put it down till you’ve gone through the whole trauma with Janie Johnson, from that first moment of horrified recognition to the thoroughly satisfying conclusion.

That’s because Cooney has touched on a core experience of adolescence: the rite of emotional passage in which teens begin to see their parents with an outsider’s critical eyes. For teenage readers, Cooney’s plot offers both a dramatic external metaphor for that inner turmoil and believable hope for eventual reconciliation.

By the finale, Janie has done a heroic bit of growing up. The mystery has been plausibly solved, she has moved from childlike complacency to dawning maturity, and both her own and her parents’ solid values and love remain intact. And at the end of this story — unlike a soap opera — the hard part is just beginning. A