On the day of his sixth birthday, Isaac Gale becomes the victim of a road traffic accident. The boy survives but lies in a coma, with his father dead and his mother lost in grief.
In the darkness only Sebastian, the boy’s imaginary friend, can help him. But Sebastian is not a friend to be trusted. He is a dark and powerful force capable of creating terrible nightmares and dark psychological visions in order to prove his worth to the devil, eradicating anyone who stands in his way. Two such people are neurologist Dr. Harish Dhami and nurse Alison Clark, who believe something far more sinister lurks in the damaged mind of their six year old coma patient.
So begins a terrifying struggle between good and evil, reality, fantasy and everything we fear.