We begin one of the most stressful episodes of Bitten four years in the past, where Ruth catches Clara using her magic to give some poor schmuck a heart attack for a few lousy bucks. Ruth pulls Clara's talisman from her ear and turns it to dust, rendering her powerless. "You'll pay for this!" exclaims Clara. Yeah, yeah.
Some time later, we see Aleister scraping together a living as a street magician. Clara introduces herself to him as "the reason you're alive." And so an unholy alliance is formed!
Now to the present-day stress at hand: Clay has been possessed by Aleister! Clay/Aleister (argh it's already so enraging!) hides Aleister's body in the storage shed, after which he bangs his own forehead on the doorframe to better sell his "Eduardo jumped me" B.S. to Jeremy and Nick. Back at Stonehaven, Ruth and Paige claim that Savannah needs her talisman to control her potentially very dangerous powers and they must leave at once for Boston to commence with her initiation ritual. Clay/Aleister suggests they just do it there at Stonehaven: why not, right? Arrrgghhh!!
We then see Clay trapped in his subconscious, which is like Stonehaven but shot with a blue filter. Aleister taunts him in this limbo world, claiming he'll take Savannah once she has her talisman and that he'll break Elena's heart by the time he's finished … and admits he's rather impressed that Clay is there at all, as his soul should be long gone. You'll find Clay is quite the fighter, fool.
Back at Stonehaven, Savannah is still shaken by the incident involving Eduardo's goon bleeding out, which wasn't her doing, as she once again insists to Elena. Elena gives her a pic from her photography days to calm her nerves during her initiation ritual, Part 1 of which includes establishing that she'll initiate through fire as her catalytic element and her familiar will be a black rat, which Paige assures her is a fine choice despite Savannah's fear of large rodents.
Elena finds some survey maps in Clay's room. which prompts her to ask him if he's building them a little cottage. Clay/Aleister changes the subject and claims he's concerned about how attached Elena is to Savannah — after all, the little witch could be dangerous until she has her talisman. Elena senses something is a little off about Clay but shrugs it off … for now.
Down in the basement, Paige is preparing for the next step of the initiation ritual, though she's soon distracted by her suitor, Nick. They make passionate love against the cage, though not before Paige tells her lover that this will be "the last time" they indulge in such pleasure. Cryptic … and, for Nick, disappointing.
After their lovemaking, Nick and Paige join Clay/Aleister and Ruth in the woods, where they've built a wooden hut for Savannah's initiation. Nick claims that Jeremy wanted it built closer to the house, which prompts Clay/Aleister to pick a fight with him, referring to Paige as "a little witch whore." They engage in fisticuffs, though Paige breaks it up before it gets really nasty. Argh!!
Elena confronts Clay/Aleister about the fight, and he claims it's all because of the WITCHES: they're tearing them apart! Then he tries to have sex with her on his desk and she punches him and runs out. We're about to have a heart attack over here.
After Jeremy confronts him about the fight, Clay/Aleister tells him there are things he doesn't know about Elena … things that happened to her at The Compound, like being forced to change in front of Rachel. Oh man, the mess this sumbitch is making!
Elena confides in Paige about Clay's behavior, wondering if perhaps it's coming from Savannah's wild talisman-less magic. Paige says it's not Savannah, though Elena is still convinced there's dark arts afoot and she hits the books, discovering the possession spell as Clay/Aleister starts preparing his own Dark Circle at an unknown location.
When Jeremy confronts Elena about her transforming in front of Rachel, she tells him she never told anyone about that. The only person who knows of that incident besides her and Rachel is … Aleister! They rush to the storage shack, though Aleister's body is gone.
In the woods, Savannah is undergoing the final step of her initiation ritual and receives her talisman. Soon after, however, she's kidnapped by Clay/Aleister, who throws her in the trunk of a car with Aleister's unconscious body propped up in the passenger seat. Dear lord.
Jeremy tells Ruth that Aleister has possessed Clay to steal Savannah. Ruth reveals that possessions spells are always fatal to those possessed — Clay as they know him is dead, and they must kill Clay's body to kill Aleister. An enraged and heartbroken Jeremy keeps this information from Elena and Nick, who discern from the survey maps in Clay's room that he took Savannah to an old foundry.
Meanwhile, in Clay's subconscious, Clay comes across his younger self … and none other than Malcolm Danvers. Clay is hesitant to descend a set of stairs, though Malcolm tells him that what's down there, "let it tear down the walls — let it set you free!"
At the foundry, Jeremy breaks the news to Elena and Nick, though they both claim Clay is strong and can still fight this. Jeremy confronts Clay/Aleister and they fight, which ends with Jeremy impaling his opponent in the stomach with a steel pipe.
In Clay's subconscious, Clay descends the stairs to the basement, where he finds an angry wolf locked in a cage. Clay opens the gate, letting the animal free … which gives his body the weapon it needs to fight Aleister's possession: transforming into a wolf himself!
It works, as Aleister awakens in the passenger seat of the car, back in his own body. He takes Savannah's talisman from the rearview mirror and releases the struggling little witch from the trunk. He gives her the talisman, saying she can now focus her powers; a quick "I am the Lock" / "I am the Key" exchange puts her under his control once again, after which he hands her a vial of Elena's blood …
Savannah drinks the blood, which is followed by a powerful energy surge. Ruth and Paige feel it all the way back at Stonehaven, where they buckle over in pain as their noses start to bleed. "It's the Beginning of the End," says a stunned Ruth as The Undoing has been unleashed!