The main character of The Evil Within is veteran police detective Sebastian “Seb” Castellanos. He is aided by his colleagues Juli “Kid” Kidman and Joseph Oda in confronting the invincible apparition Ruvik.

Three years after the events at Beacon Mental Hospital, Sebastian Castellanos has left the Krimson City Police Department and continues to be haunted by his experiences at Beacon, the disappearance of his wife Myra, and the death of his daughter Lily in a house fire.