Although the characters and cast completely changed from the beginning of this supernatural series, it maintained the trio of a vampire, werewolf and ghost living together. Hal, the vampire, is still trying to redeem himself from his evil past, Tom, the rather simple minded werewolf simply wants to fit in, and Alex is finally figuring out what she wants from life, though she's dead. Hal and Tom are both working at a restaurant, where they meet Hatch, an old guy who turns out to be the devil. His plans are to keep the supernaturals in the world from uniting--he wants them to be at war and cause chaos.
The typical, dark ending for the series finale would have them all die-- but this goes in a completely different direction with is both fitting and satisfying. I love it when a series ends on a high point and Being Human did just that.