Nine-year-old Oskar Schell is an inventor, amateur entomologist, Francophile, letter writer, pacifist, natural historian, percussionist, romantic, great explorer, jeweler, detective, vegan, and butterfly collector. When his father dies in the September 11 attacks on the World Trade Center, Oskar embarks on a quest to uncover the mystery of a key he finds in his father's closet. This journey takes him into the lives of strangers, through the five boroughs of New York, into history, to the bombings of Dresden and Hiroshima, and on an inner journey that brings him closer to a kind of peace.