In the season finale, we finally learn how Josh and Aiden first met through a series of flashbacks. Josh was working in a diner when Marcus attacked him. Aiden saved Josh, and then got him a job at the hospital where he was already working. After a year of getting to know each other, they decided to become roommates.
In present tense, Josh has moved the critically injured Aiden to the basement of the hospital and recruited Nora to bring them blood from the blood bank. Nora, of course, wants to operate but Josh and Aiden won't allow it. Sally wants to stick around to see him through but Aiden insists that she go through her door while she can, and leave Josh to watch over him.
When Celine unexpectedly relieves Josh so he can get some rest, she begs Aiden to drink her blood because she knows that it will make him heal faster—but this time it's Aiden who refuses. He knows he'd have to drain her to regain his strength.
Before Josh can leave the hospital, he runs into Nora. He thanks her for her help and her silence but, since he still won't tell her what's going on, she breaks it off. She's finally run out of patience with his secrets and apologies. Josh understands but he writes her a long letter to alleviate some of her hurt.
Back at the house, Sally is shocked to find that her door has vanished and, worse, she's become more solid. Might she have missed her only opportunity to escape this world? She has no choice but to wait and see. For now, at least, she's stuck.
Bishop is able to heal himself by draining a co-worker and, afterward, he promptly issues a challenge to Aiden. He wants the two of them to meet alone and fight to the death. Sally and Josh refuse to stand idly by. They hatch a plan to trap Bishop in the hospital basement, so that Josh, as a werewolf, can kill him. It's a good plan but it violates Aiden's code of honor so Sally locks Josh up alone instead.
In order to fight Bishop, Aiden needs his full strength so he finally takes Celine up on her offer to drink her blood. They both know she'll die but she says she'd rather give her life to Aiden than to her lung cancer. Fully healed, Aiden faces Bishop and with Sally's help, kills him. Finally, Aiden is free, at least until the escaped Dutch vampire shows up calling for Aiden to be the new ruler of Boston and to meet a mysterious vampire that neither of them will name.
In an odd twist of fate, Nora sees Josh on his way to the hospital basement and follows him. She's just in time to see Josh transform and learn his true secret. In the morning, they talk about it and Nora is surprisingly willing to deal with his "problem." What Josh doesn't know is that he scratched Nora while trying to push her out of the room. But was that scratch enough to turn her into a werewolf too?
What goes on behind the scenes for the score of Being Human? Watch this interview with composer FM Le Sieur.
Sally makes a major sacrifice to keep two of her roommates from killing each other €“ a move that will change all of the roommates€™ lives forever.
The cast reflects on how the show has changed them over the 4 seasons.