When a psychopath commits murders based on novelist Castle's books, Detective Beckett seeks his help to solve the case. He decides to work with her and uses his experiences as research for his novels.
A father recounts to his children - through a series of flashbacks - the journey he and his four best friends took leading up to him meeting their mother.
Two brothers follow their father's footsteps as hunters, fighting evil supernatural beings of many kinds, including monsters, demons, and gods that roam the earth.