Nipping at the heels of his monumentally successful first novel, Jonathan Safran Foer’s sophomore effort is quick to satisfy expectations. “Extremely Close and Incredibly Loud” is focused, compassionate, funny and sad, and it has the virtue of being quietly and humbly true.

The hero is young Oskar Schell, who has lost his father in the Sept. 11 attacks. The central narrative is Oskar’s account of his search for the lock that goes with a mystery key, which he finds in his father’s closet after his death. While Foer’s prose is perhaps too good, too well-paced and subtle for a boy of nine, it hums with the peculiar idiom and rapturous innocence of youth. Good things are “one hundred dollars,” being depressed is “wearing heavy boots,” compulsive and obscure acts of self-mutilation are “giving myself a bruise.” Foer’s admirable skill as a stylist is on full display, and if we ignore the occasionally inordinate level of sophistication, the voice he creates for his protagonist is moving, sincere and beautifully evocative of a child’s unrelenting grief in the wake of tragedy.

In a plain way, Oskar’s search for the mysterious lock is figured as a search for his lost father, and for an answer to the question “Why bother?” that plagues him after Sept. 11. As a metaphorical representation of his existential crisis, his search for meaning is a classic example of something said more effectively by implication than by explicit declaration. In another sense, the search is therapeutic and valuable to Oskar precisely because it is an elaborate metaphor. Trauma cannot be treated as one treats a bacterial infection — there is no permanent cure for the death of a father — yet Oscar’s metaphorical journey is a way for him to confront the reality of his loss while at the same time marking out new purpose and possibility. This is an elegant description of what therapy is and what therapy does: Oskar’s search is a means to access and work constructively on his psychological problem.

In Foer’s novel, fiction is the natural result of great tragedy. Characters respond to trauma by attempting to reorder their mental lives — such that the traumatic event is tempered and disarmed by metaphor. Oskar, recovering from loss, turns naturally to a symbolic search for the lost item. He knows well enough that he won’t find his father at the end of the road, but engagement with that fiction helps him cope with his loss. It isn’t always true, however, that the fantasies characters contrive are beneficial and therapeutic.

Scattered throughout the novel are letters written by Oskar’s paternal grandparents. Describing the firebombing of Dresden and the years of confusion that followed, the letters detail the strange world his grandparents construct as a means of coping with the trauma of their past. Their life together is a fantasy of oblivion. Certain places in their apartment are marked off as “nothing places,” and certain things as “nothing.” While Oskar’s fantasy is one of discovery and progress, this is one of stasis, and the result is not happy. Oskar’s grandfather can’t grow or change, and he loses himself in his past.

The addition of a Dresden narrative to a story about Sept. 11 makes “Extremely Close” oppressively bleak, and it isn’t immediately clear whether Foer will manage to save his story from black despair. As if wandering through some infernal landscape, Oskar finds traumatic loss everywhere. Such loss might be manifested as the death of a loved one, or it might simply be the loss of innocence these characters suffer when they realize that life must end in death. The ways people deal with their pain, the metaphorical worlds they inhabit in order to cope, are as diverse and strange as the people themselves. There is a woman who lives on the observation deck of the Empire State Building, a man who has driven a nail into his bed every day since his wife died, a woman who has turned her living room into a kind of shrine to her living husband.

But the thread that yokes all these tormented narratives, and the feature upon which the great beauty and great power of this book rests, is the overwhelming sincerity with which the difficulty of life is represented. As strange and sad as the characters in this novel appear, they are never figures of fun. Trauma and loss are ever-present but never banal, and the legitimacy of emotional pain is absolutely beyond question. As dark as it can be, this is a deeply felt, deeply compassionate novel. We live in an age obsessed by fear, in which horrific tragedy can and does occur — but somehow, even while organizing his novel around a terrorist attack, Foer has managed to write a book that shines with a brilliant and inspiring faith in the essential good of mankind.