In the story, Oskar discovers a key in a vase that belonged to his father, who died a year earlier in the September 11 attacks.

His relationship with his mother has also become strained, particularly as she has started dating a man named Ron, whom Oskar resents for having replaced his father.

Curious, Oskar sets out on a mission to contact every person in New York City with the last name of Black in the hope of finding the lock that belongs to the key his father left behind, creating a binder with mementos of his journey.

Oskar also discovers that his mother knew about his activities the entire time and was contacting everyone with the name Black in New York City.

In response, the people Oskar met knew ahead of time why he was coming and usually treated him in a friendly manner.

Resolving to try to move on from his father's death, Oskar bonds with Ron after finding out that he met his mother at a support group after having lost his wife and daughter in a car accident.

Before going to bed, Oskar takes out his binder and proceeds to rearrange the pages in reverse in an attempt to relive the last few hours with his father and achieve closure.

His grandmother decides to let him live with her in her apartment temporarily, which results in them becoming intimate, and he watches over Oskar from afar before meeting him.

Foer was sleeping off jet lag after returning to New York City from a trip to Spain, when he was woken by a phone call from a friend: "He said, 'You have to turn on the TV, a plane has crashed into the World Trade Center.'

Major themes of Extremely Loud & Incredibly Close include trauma, mourning, family, and the struggle between self-destruction and self-preservation.

Richard Gray stated in his book on 9/11 literature After The Fall, "If there was one thing writers agreed about in response to 9/11, it was the failure of language; the terrorist attacks made the tools of their trade seem absurd.

Rebecca Miller of the Library Journal claims "Foer nimbly explores the misunderstandings that compound when grief silences its victims.

"Few works of literature have succeeded in drawing lasting meaning, whole or fragmentary, from modernity's string of catastrophes... but Extremely Loud & Incredibly Close is one of them, providing a tool to create understanding of grief and loss.

[11] On the July/August 2005 issue of Bookmarks, the book received (4.0 out of 5) stars, with the critical summary stating, "Many admire Foer’s reach for something grand, even as they acknowledge that he hasn’t fully accomplished his task in this novel".

"[13] In a review for The New York Times, Michiko Kakutani said, "While it contains moments of shattering emotion and stunning virtuosity that attest to Mr. Foer's myriad gifts as a writer, the novel as a whole feels simultaneously contrived and improvisatory, schematic and haphazard.

[15] The Spectator stated that "Safran Foer is describing a suffering that spreads across continents and generations" and that the "book is a heartbreaker: tragic, funny, intensely moving".

[16] "Foer's excellent second novel vibrates with the details of a current tragedy but successfully explores the universal questions that trauma brings on its floodtide....

"[17] Sam Munson, in a review of two novels on catastrophe claimed, "Foer has a natural gift for choosing subjects of great import and then pitching his distinctive voice sharply enough to be heard above their historical din.

[19] Tom Hanks, Sandra Bullock, John Goodman, Viola Davis, Max von Sydow and Jeffrey Wright starred,[20] alongside 2010 Jeopardy!