The Tomorrow People writers have laid out the basic plot and are ready to begin digging into their characters' back-stories.

First up is Cara (Peyton List). While viewers already know her as one of the leaders of the Tomorrow People's underground movement and the love interest of fellow Homo Superior John Young (Luke Mitchell), little is known about her past.

Tonight's episode, "Girl, Interrupted," will fix this dearth of knowledge as it reveals why Cara is so wary of humans and why she looses control of her powers at a certain time of year.

"I think because of her circumstances, she's in a very dark place in this episode," List revealed to The Huffington Post. "Her past tends to haunt her around a specific time of year. You can definitely see that she's capable of having a dark side."

List also admitted that the script for Cara's history left her amazed.

"I think my jaw was on the floor. I actually needed some time to process it after I read it -- I was on a plane and I just sat in my seat for a while in silence," List told The Huffington Post. "I knew that it was going to be, in terms of production, a very big episode."

Stephen (Robbie Amell) is intent on using his powers to save a human classmate, but Cara refuses to do the same. Previews have revealed that she will find herself in grave danger at the hands of Ultra, a problem the love-struck Stephen is determined to fix.

"We see [Stephen's crush on Cara] grow relatively quickly," List said, according to The Huffington Post. "[But] the force behind the show is the action and the high-stakes world -- there isn't a whole lot of time where you can let your guard down and deal with things like romance, when all these things are potentially crashing down around you."

The Tomorrow People airs Wednesdays at 9 p.m. on the CW. Check out a clip for tonight's episode, "Girl Interrupted," by clicking the video below.

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