Mia Hall (Chloë Grace Moretz) thought the hardest decision she would ever face would be whether to pursue her musical dreams at Juilliard or follow a different path to be with the love of her life, her rebellious boyfriend, Adam (Jamie Blackley). But when what should have been a carefree family drive takes the lives of her mother Kat (Mireille Enos), her father (Joshua Leonard) and her little brother Teddy (Jakob Davies), everything changes in an instant, and now her own life hangs in the balance as she lies in a coma in the hospital. Caught between life and death, or otherwise known as 'limbo', for one revealing day, she flashes back into her past, and has an out-of-body experience as she watches friends and family gather at the hospital. She must make a decision that will not only decide her future, but her ultimate fate.
- Chloë Grace Moretz as Mia Hall, a 17-year old musician whose life is completely changed when her entire family is killed in a car crash, leaving her with one decision to make: whether to stay, or slip away forever.
- Mireille Enos as Kat Hall, Mia's mother who has a passion for rock-and-roll music along with the rest of her family, somewhat hesitant about Mia's love for classical music. Kat is killed in a car crash, but is seen through flashbacks throughout the film.
- Lauren Lee Smith as Willow
- Liana Liberato as Kim Schein, Mia's inseparable best friend who helps set Mia up with Adam, despite her obvious disliking of him throughout the story.
- Jamie Blackley as Adam Wilde, Mia's somewhat rebellious musician boyfriend, who sings for his band Shooting Star.
- Aliyah O'Brien as Emt
- Joshua Leonard as Danny Hall, Mia's father who takes a love of rock-and-roll with his wife, Kat, and son, Teddy and unlike his daughter, Mia. He is killed in the car crash but is seen through flash backs.
- Jakob Davies as Teddy Hall, Mia's little brother who she is very fond of. Mia worries constantly about Teddy through the book because it is unclear whether he is killed at first or not.