Having discovered that the traitor used by demon-calling witch-hunter Eben is Jake's presumed-dead brother Nick, the circle has a hard time chasing him and working out his tragic story. A spell devised by the 'Blackwell half-sisters' to reveal the missing crystal also grants them a vision of its history, starring John as black magician scheming to wreck the previous circle and construct the kids' one to his design, for one by fathering them. Grant is back, but can only serve a shoulder for Diane to cry upon after her non-biological father admits having attempted to protect her, also by wrong means, including the murder of Cassie's grandmother Amelia. Adam found the last crystal after undoing its cloaking, but Nick overheard the outcome and grasps it, to exchange with Even for the demon he needs to survive, forcing Jake and John's party to fight them, ending in Faye saving her new lover Adam and Jake by stabbing Nick. The circle must now decide whether to trust John to help protect them by constructing the crystal skull against Eben.
- At the house, Melissa doesn't believe they saw Nick. John Blackwell suggests that when Nick drowned, the demon kept him alive. Melissa is excited he's alive, but they point out it's not really him.
"He definitely more into massacring people than he used to be," Faye says.
Jake says the witch hunters were mauled like by an animal. Melissa wants to help him, but Jake insists it's too late.
Diana refuses to talk to Blackwell, saying she doesn't trust him. He sets Cassie on using her Balcoin blood to find the crystal in the high school. He reassures her he just wants what's best for them.
Cassie heads to the school. She draws the symbol on the floor and then immediately sees her young mom walk by holding the crystal, shouting for Elizabeth.
At Diana's, Cassie tells her about seeing her mom calling for Diana's. Cassie suggests that together they might be able to see what happened to their mothers. Diana doesn't want to use dark magic.
"All we need is your blood, so you can keep your moral outrage intact," Cassie says, only partly joking. Diana agrees.
They plan to try tomorrow at the prom. Cassie's never been to one before. "It usually doesn't involve ancient crystals and time travel," Diana says.
Faye follows Jake home, suggesting maybe he's over-reacting a little to Melissa's feelings for Nick. He takes out a dagger to protect him from Nick if he comes back.
Charles checks that Diana is staying away from Blackwell. He gives her a present for prom, a gold flower necklace that used to belong to her mother. He offers to give her a ride to school.
At school, Cassie tells Adam the plan. They make plans to meet at the house before prom.
Charles drops Diana off at school. Dawn tells Charles she'll talk to Blackwell. Charles is worried about letting the most evil man they know get that much power.
Later, Melissa is the first to the house. Nick is waiting for her. He looks half dead and wants her help. He wants a crystal. He says he's dying. She promises to help him and tries to reassure him, but he shouts for the crystal. When Adam comes in, Nick knocks Melissa over and runs.
Blackwell talks to Dawn, thinking Charles is the problem. She points out people saw him fighting with Charles and will know it's him if something happens to Charles. Blackwell says he has dirt on Charles that will break his bond with Diana. He leaves and Dawn immediately calls Charles, but she gets his voice mail.
At the house, they pop champagne and try not to think about Nick. Melissa tries to make a case for Nick, but they think he's a threat.
They head to prom. Cassie and Diana go get coffee and Diana sees Grant. Cassie prods her to talk to him but then interrupts when she gets a text about Nick. Diana invites Grant over later.
Charles gets a call -- it's the conversation Cassie had with Amelia the night she died. Blackwell lurks outside his house. Dawn calls Charles again, but all he hears is Amelia and Cassie. Charles starts to freak out. The sinks starts spraying and his stove flames, lighting his kitchen on fire just life Amelia's. He slips on the water and lands on the floor. He asks Amelia to forgive him.
Charles opens his eyes and sees that everything in normal in his kitchen.
The circle finds an empty classroom. Cassie cuts her finger and draws the symbol, then Diana does while the others stand watch outside. They're suddenly in 1995.
Amelia goes to tell Elizabeth she needs to get out of town. Amelia says something bad is going to happen and she should take Diana and leave. It's the day of the boat fire. Amelia knew.
Demon Nick arrives at the dance. A cop tries to stop him, but Nick snaps his neck and goes in.
In 1995, Amelia tells Elizabeth that John isn't what they thought he was and they shouldn't have trusted him. Elizabeth knows John is dangerous. Amelia admits she was wrong about him and just found out a few days ago. Elizabeth can't believe she waited to say something.
Amelia knows Diana is his. She apologizes for letting John into their lives, but urges Elizabeth to leave town. Elizabeth thinks John will tell Charles about Diana if she tries to leave. She tells Amelia she's done listening to her and leaves.
They follow Amelia and the crystal.
Standing guard outside the room, Melissa wallows in self-pity over the fact that they're never going to have normal lives. Adam cheers her up by turning up the music and putting on mood lighting. He asks her to dance.
On the dance floor, Faye reminds Jake about him standing her up two years ago. She waited three hours. She forces him to dance. She knows he feels guilty about Nick, but she tells him the circle are the ones who didn't help him, not Jake.
Still in 1995, Amelia goes to return her crystal to Adam's grandfather. He gave her the crystal to protect herself from Blackwell. She tells him she's planning to take Cassie and leave.
Amelia confesses that Ethan is turning Blackwell over to the witch hunters right now. She says Blackwell made the six girls in her circle get pregnant. He used magic on the other four to make sure they conceived. Mr. Conant says Blackwell is building a circle for himself.
Watching, Cassie realizes her father planned them.
Mr. Conant tells Amelia he'll cloak the crystal and hide it in the trophy case in case she needs it. She tells him to tell Ethan she doesn't love him, for his own safety.
Cassie and Diana now know they're being used, but for what?
They come back to the present. Cassie acknowledges Diana was right. But that's not enough for Diana, who says she needs to apologize to the circle and that it's Cassie's fault he's in their lives at all. Diana compares Cassie's blindness to her mother Amelia's, whom Diana now blames for her mother's death. Diana runs out.
Adam and Melissa come in for a recap. After Cassie tells them Blackwell is using them, they hear a noise in the hall. It's Nick, he's going for the crystal. He rounds a corner and runs into Dawn, then blows by her.
Faye and Jake run into them and head for the trophy case. Adam is unlocking it when Nick body slams him into the case and grabs the crystal. The circle takes off after Nick.
"I knew I should have brought demon-chasing shoes," Faye complains.
Diana comes home to find her father huddled on the kitchen floor. He tells her all he ever wanted to do was protect her. He tells her he's done terrible things. He's freaking out and paranoid. He tells her to go upstairs and pack.
He says Amelia is haunting him because of "what I did."
Diana realizes he killed Cassie's mom. She runs outside into the street. Grant pulls up and hugs her. Blackwell sees the whole scene as she breaks down.
The circle, minus Diana, follows Nick to a wrecking yard. "Why is it always spooky old dirty places with him? Why couldn't he hide in a mall or a nice hotel?" Faye whines.
They have to find the crystal and keep it away from Blackwell.
As they're looking, Jake apologizes to Faye for bailing on prom two years ago. They follow a noise.
Cassie, Melissa and Adam see Nick meet Eben. Nick wants to trade. Cassie sees what's happening and uses dark magic to turn on the junk cars and rip the crystal out of Nick's hand. Eben uses his borrowed magic to fling Cassie through the air. He starts racing scrap cars at the circle.
Faye and Jake are unprotected as a car barrels toward them. At the last second, another cuts in its path, saving them. It's Blackwell, saying he'll deal with Eben.
Eben flips a car on top of Blackwell.
Nick finds Cassie unconscious on the ground and goes for her crystal. Jake sees his brother and tackles him with his knife. They struggle over it but Jake lets up, feeling for his brother. Nick doesn't have the same problem and starts to choke Jake, showing no signs of letting up.
Suddenly, he stops. Melissa stabbed him in the back. Nick drops to the ground, really dead this time. She tells Jake he was right, that wasn't Nick.
The rest of the circle converges as Cassie wakes up. They look for the crystal but Blackwell walks over and picks it up. Blackwell says Eben got away and took Faye. He says they can save Faye by building the skull.