Well. Here’s a novel, Do Not Become Alarmed by Maile Meloy, that feels, in every respect, like it should be a literary event, a big summer book. Its author is held in very high regard, rightly; it has a strong premise, a vacation that goes frighteningly awry; it addresses big topics, money, race, privilege, and its plotlines involve high stakes, kidnapping, adultery, death. Its characters are granted space to change and grow — something we demand very strictly of fictional people, if less often of real ones. Its writing is uniformly excellent.

So what happened?

"Do Not Become Alarmed," by Maile Meloy (Riverhead)

“Do Not Become Alarmed,” Meloy’s fifth book for adults — she has also written middle-grade fiction — concerns two American families on a cruise to Central America. The mothers, Liv and Nora, are cousins, although as close as sisters. Each has a husband and two children. Spread among them are various individuals (a borderline-autistic child, a famous actor, a diabetic) who demand slightly specialized varieties of love from the women.

The mood is one of peril. “The disaster will be the thing you don’t expect,” Liv, the book’s best character, thinks. “So you just have to expect everything.” Meloy offers a few teasing moments of unease before finally delivering an actual disaster: the pair’s four children wander off from a beach where they’ve stopped (strongly implied to be in Costa Rica) with two friends made onboard, Argentines. In search of an innocuous ad­ven­ture — as their parents were, in planning the trip — they fall into the hands of drug dealers. Now, Liv and Nora, who live in the weird simultaneous state of utter anxiety and utter security that so many affluent American mothers and fathers do, can begin to freak out in earnest.

Meloy’s best work is her short fiction, particularly the lithe, lean stories, as alive and elusive as fish in a stream, of the masterful “Half in Love.” But the novel asks for different strengths. Meloy is too gifted and curious to be boring, and innumerable stray lines glimmer from the pages of “Do Not Become Alarmed” — when, for instance, Liv feels overlooked sexually and then wonders at herselfabout having believed erroneously that “motherhood had cauterized her vanity” or when she ponders the choice to become a parent in the first place: “How could you know? It was a decision made at the brink of a widening abyss, based on rumors from the other side.”

But despite these moments, the book is essentially a write-off. To begin with, it’s a thriller without thrills. The parents’ pursuit of their children is hysterical but static, mistaking emotion for action, while the children’s experience itself is implausible and dull. (The book constantly tells on itself, as bad ones always do. “A man had shot a gun in them, like in a movie,” one of the children thinks. Yep.) The drug dealers are outlandishly stupid characters. Liv, Nora and their families are more carefully wrought, but they’re in too farfetched a situation to achieve escape velocity from the novel they’re stuck in. Never do they feel, even briefly, as though they could exist before the book’s first page or after its last.

These may seem like technical problems, but in fact they spring from the book’s bedrock failure, which lies in its design, its desultory attempts at bigness, at significance. “The karmic bus had mowed her down,” Liv thinks. “She was being punished for living in a false world, spongy and insulated from the reality around her. For living in a house with an alarm system, in a neighborhood where the only Latinos were gardeners.”

Maile Meloys best work is her short fiction, particularly the lithe, lean stories. (Courtesy of Maile Meloy)

This should be a first premise, not a conclusion. Ever since David Foster Wallace published his unsurpassable nonfiction novella A Supposedly Fun Thing I’ll Never Do Again ,” the cruise ship has come to represent something peculiarly awful about American culture, something to do with the indefensible gap between the ship’s extravagances and the impoverished shores it primly and massively grazes, before departing again for the safety of open water. The novelists Adam Haslett, T.C. Boyle and Lydia Millet have all alit upon it as a useful symbol in just the past few years, the cosseted catatonia, the anhedonic hedonism. The eating.

Meloy is content to deploy that symbol without investigating it. Again and again, “Do Not Become Alarmed” trots out a vague sense of social responsibility, while focusing emotionally on a handful of nervous Americans. There’s something ugly about that; the whole project, in a way, replicates the colonialism it deplores, plundering Central America for its sense of risk, then returning home with a safe little keepsake frisson of fear, of self-doubt. The book’s few native characters are indistinct, idealized and therefore oddly dehumanized, except for one, a guide, who is endowed with such preternatural sexual skill that his depiction veers — although I have no doubt of Meloy’s goodwill — treacherously close to the racism of an earlier time.

At its best moments, “Do Not Become Alarmed” captures the anxiety of being the kind of parent with the least right to be anxious, a rich American one, the feeling that even our best efforts (the most enormous, cocooning cruise ship!) cannot safeguard us from danger. It’s an interesting notion, but because Meloy ventures half-heartedly into her ambitious themes, it barely emerges. “Their parents are American,” one local character thinks. “They don’t know anything.” This book is supposed to be a sally against that blindness. It only seems like proof of it.

Charles Finch is the author, most recently, of The Inheritance .”

do not become alarmed

By Maile Meloy

Riverhead. 342 pp. $27