It tells the story of an American high school girl, Lennie Walker, struggling to cope with the sudden death of her older sister.

Lennon Walker, called Lennie or Len, is a high school student whose love for nature and band comforts her throughout the day.

Bailey's sudden death from heart arrhythmia while she is rehearsing the lead in the play Romeo and Juliet throws Lennie, Gram and Uncle Big into a depression that takes some time to overcome.

Lennie attempts to cope with her loss by leaving notes and poems throughout the town, which often contain conversations the sisters had before Bailey's death.

Lennie walks away from the grave with a smile, knowing that her sister would have forgiven her and that the only way to deal with grief is to accept that it is a part of life and to look ahead to the future.

Robert Dunbar described the tone of The Sky Is Everywhere as "at times, skittish and witty", saying that "there is an often poignant dissection of grief, of guilt, and their effect on the maturing young as they struggle to accommodate themselves.

Shauna Yusko of Booklist praised the book saying, "Readers will identify with her and root for her to finally make the first steps toward healing.

"[3] Likewise, News designer Judy Smith said that The Sky Is Everywhere was, "written for a young adult audience, [but] will be enjoyed by anyone fascinated with the randomness of life.

"[4] Vanessa Lewis, co-founder of a children's bookshop, said that The Sky Is Everywhere had a gorgeous cover, was an "exploration of grief, love, and life," and was hard to put down.

[8] Robert Johnson of VOYA readers said that, "The feelings associated with a sibling's death are expressed accurately, changing from sadness to incredulity to laughing and crying at the same time.

[10] In October 2019, it was announced A24 and Apple TV+ would produce the film, with Josephine Decker directing, and Nelson writing the screenplay.