Hamilton's cybersavvy Hamlet is Henry Shaw, 17 years old, with a slight tendency to brood. He imagines his mother would describe him as "perfectly amiable ... as if I were an 18th century lapdog ... I was in the chess club, I took photographs for the yearbook, I assisted in the computer lab ... I usually finished my homework. I shut up and did as I was told."

This model teen boots up the family computer and discovers that his mother, Beth Shaw, a musician, has been playing horizontal duets with a violinist named Richard Pollaco. Henry got his mother wired (if you hear Freudian overtones in that, they're intentional); he has her password. "When I first stumbled into her e-mail file I didn't mean to. It was accidental. It was about as easy to type in her password as mine; I wasn't even thinking, I had no plan, nothing premeditated, no scheme in place. I realized my error as the icons slowly formed themselves before me in their beamy pleased way."

Soon he's logging on daily, sometimes hourly, for the latest sweaty chapter in the saga (kind of a twist on Internet addiction and e-publishing). Not only does Beth Shaw e-mail her lover with passionate frequency, she shares every clinch and grope and quarrel with her best pal Jane. This is convenient for Henry and for the unfolding of the story -- too convenient, in fact, to be very plausible.

Friend Jane lives back in Vermont, in the happy little town the Shaws used to inhabit before Henry's father, Kevin, got a job teaching history in Chicago. And what is Kevin doing while his spouse cheats and his son spies? He blithely takes Henry's sister, Elvira, off to Civil War reenactments. "My father's general enthusiasm was almost always with him ... like a cloud circling him, like bees, buzzing around a large petally flower. That joy of his was insistent ... Sure, the Big Emptiness was out in the world, sure it was and he knew it, and so what?" Poor myopic Kevin is just about the only character worth rooting for in this self-absorbed mess of a family.

Henry takes a stab at losing himself in teenage distractions, including a blond named Lily. But his mother continues to obsess him. He catches her fighting with his father, and it might as well be in flagrante delicto: "What was there better, in its way, than that scene, my small mother trembling open, the hot sound of her breathing towards me, the swimmy heat and flush of the air?" A psychic reveals that Beth and Henry were married in another life, which leads son and reader into some queasy Oedipal reveries.

Two of Hamilton's previous novels, Oprah Winfrey picks "A Map of the World" and "The Book of Ruth," follow women through hell (wrongful child molestation charges, for instance). In "Disobedience" Beth Shaw's hell is mostly of her own making, and Hamilton doesn't seem all that interested in its torments. Instead she trains her attention on how the noncombatant members of the family fare while Beth does battle with her wayward heart. Puberty threatens Elvira's budding career as a hardcore Civil War reenactor, a pastime described in distracting detail. Desperation creeps into Kevin's relentless good cheer; he knows something's up, he just won't admit it. Gloomy Henry more or less keeps Beth's secret; you can almost see the clouds gathering over his head.

By the time the inevitable storm breaks, the air has gotten pretty thick. Claustrophobia, brought on by Henry's obsessive need to keep Mommy under the microscope, sets in way too soon. Hamilton does know how to pace a story, but it isn't enough to make you happy about sitting through this drama. Henry, despite the similarities, can't claim to be Hamlet. The melancholy Dane would fall on his sword if asked to deliver this bit of dime-store philosophy: "I was sure that I was permitted, as their son, to exercise moral judgment over the Shaws, even if I did so with no one else, including myself. They had chosen, after all, to play a certain game and it seemed to me that if you entered into it willingly, then you had to observe the regulations. If you stepped out of bounds it followed that you could lose everything. You might very well end up with nothing." You might indeed.