John Winchester raised his two sons Sam and Dean to hunt and kill all things that go "bump in the night" after his wife Mary was murdered by an evil supernatural being when the boys were little. 22 years later the brothers set out on a journey, fighting evil along the way, to find their recently-missing father; when they finally do he reveals he knows what demon killed their mother and has found a way to track and kill it. Meanwhile, Sam develops frightening abilities such as seeing visions of people dying before it actually happens. These visions are somehow connected to the demon that murdered his mother and its mysterious plans that seem to be all about Sam. When their father dies striking a deal with that very same demon, the brothers determine to finish his crusade. But disturbing revelations about Sam's part in the demon's apocalyptic plan are presented when John's dying last words to Dean are revealed.