The Secret Circle The Secret Circle

Now that The Secret Circle's coven has forged a semi-united front, the group's members will face new challenges as they struggle to understand their powers and whether to use them for good or evil, all while Cassie (Britt Robertson) tries to uncover the mysteries of their parents' coven.

Meet The Secret Circle's Secret Coven

In last week's episode, Cassie learned that her mother may not have been an innocent witch, as an old friend of her mother's revealed that Amelia Blake had done something far worse than kill their former best friend, Heather (Camille Sullivan). In locating Heather, the CW series will take a seriously dark turn that will include at least one death. (Watch the trailer.)

"Not only is it when I think the show really finds its footing in what it is, it also is the episode when we tip off in the dark side," Thomas Dekker says. "The show gets darker and darker and heavier and more frightening and this is the episode where that really begins."

Heather, who'd actually be better off dead, has been in a catatonic state since the mysterious fire 16 years ago that claimed most of the new coven's parents. Cassie will enlist the help of Faye (Phoebe Tonkin) — and she'll need it when Heather becomes possessed.

"This is the first episode where you get to see Cassie wanting to learn more about magic and wanting to really discover what happened with her mom with the rest of the adults 16 years ago when her mom fled and why her mom fled," Robertson says.

Meet Phoebe Tonkin, The Secret Circle's bad girl

Though Faye is known for taking magic too far, even she will be terrified by what's in store for them. "Faye is a very controlling person, she likes to be the one that's creating these situations and when it's coming from somewhere else, it's just terrifying," Tonkin says.

Enlisting an enemy for help may not be the smartest idea, but it does showcase a vulnerable side of Faye. "Cassie is slowly trying to take everything away from her," Tonkin says. "She's starting to feel pretty threatened by Cassie." Adds Robertson: "The whole episode they spend together and they're stuck in this house and they basically have to save each other from various different situations. You get to see their relationship in a completely different light."

This is one of many incidents that will set off a power struggle within the coven. "Everyone's got different intentions and everyone wants to use this magic for different things," Tonkin says. "Everyone's going to start swapping sides, and people that want to use it for good are going to start seeing that they can use it for evil and that they can better themselves. There's going to be a lot of switching intentions in the circle."

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Look for Cassie to test being a leader in the coven as well. "As Diana has always been the leader for them, Cassie has a better understanding, along with the rest of the group, of who they are and what they can control and what they can take on," Robertson teases.

The Secret Circle airs Thursdays at 9/8c on The CW.