Poor Chin just can't catch a break.

On Friday's episode of Hawaii Five-0, not only does Chin (Daniel Dae Kim) get a severe ass-whooping at the hands of Gabriel Waincroft (Christopher Sean) - who then appears to miraculously survive a nasty fall onto the roof of a car - but we finally discover the big secret Chin's latest love interest, Abby Dunn (Julie Benz), has been hiding. She's actually a plant, sent to infiltrate 5-0 and get some dirt on them. Who's she working for? Federal prosecutor Robert Coughlin (guest star Ingo Rademacher), who happens to be the brother of Rex Coughlin (Robert Knepper).

If that name rings a bell, you may remember Rex as the Internal Affairs investigator who arrested Danny and Chin last season, and was killed when Gabriel stabbed him in the eye. Now, Robert is back to avenge his brother's murder, and is hell-bent on exposing the rule-breaking behavior by the members of Five-0 in the process.

TVGuide.com chatted with Benz about the big Abby reveal, and whether there's still a chance for a romance between her and Chin.

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People are going to be so disappointed about Abby! Did you know from the start that her character was actually a mole?
Julie Benz:
I found out probably about three episodes in. The producers came and told me, and then I had to keep it a secret from the cast. I wasn't allowed to tell anybody.

How did you react to the news?
Benz:
I was excited and disappointed at the same time. I was excited from the standpoint of, every character on that show has some sort of secret. So, I was excited to finally find out what Abby's secret was and what she was not revealing. ... I was disappointed though, because I'm a big fan of the show and I really want Chin to find happiness. He's had quite a lot of heartbreak in his life. So, I was disappointed from that aspect, as a fan.

So what can you tell us about her motivations for working for Coughlin?
Benz:
She's Internal Affairs. She's investigating [5-0], and she hasn't found anything. In this week's episode, we just see her behind the window, and she's not happy with the way the questioning's going. You do see that in her facial expression. You see that she's in a very uncomfortable position, and something's not ringing truthful to her. ... This is f---ed up, basically.

Will she come clean to Chin and the rest of the Five-0 crew?
Benz:
She's put in a really bad situation where she has to choose between her job and her heart. She has to make that choice. ... I think she's developed real feelings for Chin over time. What probably started as a way for her to get close to the 5-0 has turned into actual, real feelings, and now she has to confess to this person that she really cares about that she's investigating him. That's a very difficult, complicated conversation.

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Do you think there was a turning point when she started to have genuine feelings for Chin?
Benz:
After their first night together, we see her peeking around the corner when he takes the phone call from the 5-0 that [they] need to go off and solve a crime. I think there's a moment there where she really is just taking him in and that's where her feelings are really starting to develop. ... She's stuck between a rock and a hard place. I honestly believe she probably started the flirtation with Chin - obviously he's an attractive guy - [because] she figured, OK, this is an easy way in. And then she really just started falling for him, and it's really put her into a bad situation.

We saw Abby lie to Chin about being back in San Francisco at the end of the last episode. Was that part of her ruse, or is she trying to sort out her feelings?
Benz:
I think it's a mix of both. I think she's realized she's gotten too close, and she needs to get some space. And also, it provides her a little bit of coverage so she can figure out what's going on with the investigation. But I think she needed to get some personal space away [from Chin], because things were getting too intimate for her.

Is there still hope for her and Chin? Or is this the end of "Chibby"?
Benz:
I hope not, because as a fan of the show, I want to see Chin have a happy ending. I want to see him have a happy relationship. He's been through the wringer, and he deserves to have a little bit of happiness. ... Abby at her core is a good person. She's doing her job, and when she finds out that she's part of a personal vendetta, that really upsets her. It bothers her. Because she really respects what the 5-0's doing. She has not found any kind of abuse of power on their part. ... I do think there's hope. I think it'll take a lot of forgiveness, [if] she's up-front and, before any serious damage can be done to the 5-0, she confesses to them what's going on.

What can we look forward to in the next episode?
Benz:
She confronts Coughlin head-on, and has to really soul-search on her own to figure out what she's going to do. Is she going to choose her job or choose her heart? Coughlin's an evil dude. He's not good. He's just looking for anything to take down the 5-0. ... Abby at her core is a good cop. She's a good detective. ... If there's nothing to pin on them, there's nothing to pin on them. But Coughlin is really pushing her, and we get to see her stand up to him, which is fantastic.

Hawaii Five-0 airs Fridays at 9/8c on CBS. Check out a sneak peek of the episode below.

(Full disclosure: TVGuide.com is owned by CBS.)