Picture a wilderness training program like Outward Bound, then add a dark history and shadowy motives. Welcome to “The Islanders,” acclaimed Portland author Lewis Robinson’s gripping and deeply satisfying novel of courage, camaraderie and deception.

“The Islanders,” by Lewis Robinson. Islandport Press, $18.95

The island in question is a 2,000-acre spruce and granite idyll, known as Whaleback, off the coast of Maine. It’s the exclusive second home to a clan of moneyed owners who are, by rights, members of the Islanders Club. The Club, with a capital “C,” is all about history, legacy and privilege, attributes that need to be valued and protected. The island is also the backdrop for tensions between wealthy Club members and those they wish to help.

So begins an effort to recruit 50 high school seniors from around the nation — defiant rule-breaking teens in need of training, one from each state. The program is dubbed Whaleback Island Leadership Detail, or WILD, and it offers a vague sort of apprenticeship. If they succeed, recruits will be set up for life, or so they’re promised. The program starts in the fall, after islanders have left for the season. Recruits are assigned to six huddles of eight or nine members each. Their days are a litany of exercises and tests — pushups and obstacle course walls, capsize drills in 48-degree water and timed runs on trails. There are no snacks, no phones, no contact with the outside world.

“Each day, morning swim starts at sunrise,” says one of the six military-trained instructors. “Keep track of the time. Stick together, support each other, embrace the privilege of being here. You’ve been chosen for this, so do your part.”

The book centers on the Grunewald Huddle, named for its instructor, a 60-something war veteran and bully, Dick Grunewald. But the book’s true center and narrator is Walt McNamara, a high school hockey star turned loose cannon, who’s torn up about his family falling apart. After vandalizing the art room at school, Walt is expelled from St. Bart’s, the prep school where his ailing dad runs the maintenance department. Other key figures include Aubrey, a track runner who’s mysteriously mute through much of the book, and becomes Walt’s girlfriend; and the ever feisty Tess.

“For all of us it was exhilarating to know that we could just lie down on the ground in October for the night on an island in the middle of the ocean and survive,” Walt says. “We felt cold and hungry, but our bodies were buzzing from having been wedged all together. This seemed to be part of the process of forgetting our former lives.”

No sooner does the Grunewald Huddle start to function as a unit — “a single living organism,” as Walt describes it — than they start to question some of the strange goings-on around them. All manner of horrific accidents and pranks keep happening, such as when a recruit from the Janowski Huddle is mistakenly shot in the thigh during target practice. Several attempts to get help, via helicopter and boat, somehow never quite pan out.

“I’m telling you right now,” Grunewald says, “they’re asking you to trust them without knowing much… I’ve worked for them for a long time, and I’ve never felt as unsure about their motives than I am now. You have to decide for yourself what’s right. You’ve got to follow your gut.”

As the story alternates between Walt’s time in high school and his life on the island, what emerges is a growing unease about the program and its operators. Suffice to say, this book could well have been named “Gaslight,” if that title weren’t already taken. As it turns out, the WILD program is more like militia training, for reasons that gradually unfold.

Robinson has written a first-rate, often lyrical page-turner that is, at heart, a coming-of-age-story, character-driven and suspenseful. The landscape, too, is nearly cinematic, with its pristine golf course and yachts, unspoiled deep greens and blues surrounding graceful mansions.

Yet the triumph of this book is its misfit teens who band together, demanding the truth from the Club’s leaders and refusing to go along with their deceit and lies. By the end, Robinson has taken readers – and his characters – on an emotional rollercoaster. We leave solidly cheering on these recruits.

Joan Silverman writes op-eds, essays and book reviews. Her work has appeared in numerous publications including The Christian Science Monitor, Chicago Tribune and Dallas Morning News. She is the author of “Someday This Will Fit,” a collection of linked essays.