Extremely Loud and Incredibly Close, Jonathan Safran Foer's ambitious second novel (after Everything is Illuminated), follows nine-year-old Oskar Schell as he navigates New York City on a quest to unlock the secrets of a mysterious key and its connection to his father, who died in the collapse of the World Trade Center on 09/11. Most of all, the novel is an exploration of grief set against the cultural backdrop of post-09/11 America, interspersed with secondary narrations by Oskar’s grandparents, whose lives parallel their grandson’s in significant ways. Typically, one of the secondary narrators provides one chapter for each chapter of Oskar's narration. Grandma's story is told via letters she writes to Oskar, whereas Grandpa's letters have been written over the course of decades, and are all addressed to his son (Oskar's father, Thomas Schell Jr.).
Oskar lives in Manhattan with his mother, who is often absent because of work. His overly protective Grandma lives across the street. An extremely emotional and intelligent child, Oskar is often over-stimulated by his environment, and often falls victim to his many fears and phobias. His natural eccentricities have only been exacerbated in the wake of his father's death, which haunts him constantly.
After he finds a mysterious key in his father’s closet, Oskar meticulously plans a quest to find its purpose, hoping that by finding its owner, he might find out more about his father's last days. Because the key was in an envelope with the name "Black" on it, Oskar travels all over the five boroughs to meet every person with the family name "Black" that he can find. He interviews a slew of interesting and eccentric characters along the way, including Abby Black, who seems to know more about the key than she is willing to admit, and Mr. Black, an old man who agrees to accompany him on the journey.
The latter half of the novel focuses more closely on Oskar's relationships with his mother, his Grandma, and his Grandpa, whom he believes is merely the renter in his Grandma's extra bedroom.
After eight months of searching for the lock, Oskar is no closer to the truth. After meeting his Grandpa, he enlists the man's help to dig up his father's empty coffin. When they accomplish the task, Grandpa fills the coffin with the many unsent letters he has written Thomas Jr. over the years.
The mystery of the key is solved by Abby Black's anticlimactic confession, in which she admits that it belongs to her ex-husband William, who had, in a quest similar been Oskar's, been searching for the key after learning that his estranged father had wanted him to have it.
Oskar’s narration concludes with his emotional reconnection with his mother, whom he has spent much of the novel resenting. He learns that she has not only been aware of but also secretly helping facilitate his quest, and he admits his love for her. Tied in with this is his more mature acceptance of his father's death. At the end, Oskar is able to embrace memories of his father without having them tainted by the tragic events of 09/11.
The secondary narrations of Extremely Loud and Incredibly Close tell different stories that overlap with one another and occasionally with Oskar's. Thomas Schell Sr.’s narration flows erratically as he writes letters to his son (Oskar’s father), whom he abandoned before Thomas Jr. was born. His story begins in his teenage years in Dresden, Germany, where he meets and falls in love with Anna, who becomes pregnant with his child. However, her entire family, save her younger sister (who grows into Grandma), perishes in the attacks, and he is forever scarred by that tragedy. Eventually, he moves to New York City, where he loses his ability to speak. There, he meets Grandma, and they marry, forging a strange, emotionally distant relationship. Once she becomes pregnant, he panics and leaves her for Germany. He lived away, writing unsent letters to Thomas Jr., until he returned on 09/11 to live in Grandma's extra room. It was there that he met Oskar, and helped with the graveyard scheme. In the end, Thomas finds he is still afraid to commit and leaves for the airport, where Grandma joins him.
Grandma’s narration is also written in the form of letters. She writes to Oskar from the airport, where we eventually learn she has joined Thomas Sr. She writes to Oskar about her life as a young girl in Dresden, as an immigrant in New York City, and a wife to the Grandpa he has never known. She tries to explain her decisions, all of which are riddled with self-doubt and depression, and hopes to influence Oskar's strained relationship with his mother. She abandons Oskar at the end of the novel to follow Thomas to the airport, where they intend to spend the rest of their lives together.
The novel’s text is enhanced by photographs from Oskar’s scrapbook, which contribute to its unconventional method of storytelling.