Marvel's Agent Carter type TV Show network ABC

Peggy Carter has a very big decision to make in the season finale of Marvel’s Agent Carter. But first she’ll have to tussle with the season’s big bad, Whitney Frost, and align herself with some unsavory characters to do so.

During Tuesday’s finale, Peggy (Hayley Atwell) teams up with Whitney Frost’s (Wynn Everett) psychotic mobster boyfriend Manfredi (Ken Marino) in a bid to rid the brilliant starlet of the Zero Matter once and for all. “At this point, you realize the extent of Whitney’s abuse of power,” Atwell tells EW. “She’s going to lose everything around her in a desperate attempt to get more and more and more of it, similar to like an addict would. I think she’s kind of an addict, and Zero Matter is her drug of choice.

“Whitney is someone who is very dangerous,” Atwell continues. “She’s a psychopath, even to the point where her own people have turned against her. What’s scary is that because Whitney’s so bright and so smart, you don’t know what she’s going to do next or what her next move is. It’s quite scary for Peggy to try to work out. Unfortunately, it happens that Whitney’s used her brain for the force of evil.”

Whitney also hit Peggy where it hurts this season, basically turning Jason Wilkes (Reggie Austin) against her in order to secure the uranium rods that could help them rip another rift to the source of Zero Matter. Still, Peggy recognizes that Jason was desperate to save himself, making her a little more forgiving in the finale. “She’s starting to witness that Zero Matter is an intoxicating thing, so I think she has more empathy than just writing him off that he’s evil now,” Atwell says. “She can forgive him, because she’s had to ask for forgiveness herself for the part that she played in getting him to where he is. Things are not as black and white for her, but it puts a huge tension on whether or not they end up together. It’s Peggy’s luck that she’s attracted to someone that she can’t have, whether it’s physically because he’s invisible, or because he’s losing his mind to this Dark Force, and that Peggy’s played a part in that. It’s Peggy’s self-fulfilling prophecy, I guess.”

Therein lies Peggy’s choice in the finale: Does she give it a go with Jason after all that’s happened, or could there be hope for Peggy and Sousa (Enver Gjokaj)? “It’s a real struggle for her because she really wants to love,” Atwell says. “She has a great capacity to love, but she’s been hurt so much before by losing the person that she loves in Captain America that she’s stuck now in a situation where she goes, ‘Even if I open up myself to one of them, that doesn’t necessarily mean it can go well. I could end up harming them even more and end up alone again.’ I think the whole thing is quite difficult and dangerous for her emotionally.”

The season finale of Marvel’s Agent Carter airs Tuesday at 9 p.m. ET on ABC.