As determined detective Kate Beckett on "Castle," Stana Katic has plenty of experience playing with guns, chasing bad guys and problem solving. This Monday she'll be grappling with a whole new issue that hasn't been previously addressed on the show -- post traumatic stress disorder (PTSD). When Beckett finds herself facing a sniper, memories of her own shooting surface and send her into a downward spiral. I talked to Katic about Beckett's struggle, why Castle (Natha Fillion) is powerless to help and what she thinks the long term prospects for Beckett and Castle would be -- as  a couple. 

Beckett, who was shot last season, discovers that PTSD isn't something she can control -- or predict. "Without her realizing it, this fear that's been sitting in a deep, dark corner for Beckett kind of mimics her own experience from the season finale from last year," Katic says. "What I learned in researching PTSD is that you never know what's going to trigger it. It can be something as simple as snow. Sometimes it comes on like a big bulldozer and sometimes it sneaks up on you. And for someone like Kate, who's so interested in being in control, that's hard to manage." 

While Beckett and Castle have weathered near-death experiences and shoot outs, Beckett's PTSD may be the most difficult for Castle to handle. "It's a different journey for the two of them," Katic says. "Castle is immobilized, because he wants to help the woman he loves but he doesn't have the tools needed to help her. For the first time he has to just sit on the sidelines and watch her go through this on her own. Guys always want to take on the protector thing, and this time she's really heavily reliant on Esposito (Jon Huertas), who's the only person whose been through this himself."
 
Beckett's usual approach to problems -- to put on a brave face and soldier on -- isn't going to work this time. "She has to face her on mortality," Katic says. "This is not something you can force under the rug. It's something you have to face head on. In her case, she needs help from those around her, and Esposito guides her back to that experience in the graveyard, and encourages her to address something she's been avoiding. Who is this person that shot you, why did they do it and how do you normalize yourself in the face of that? She decides to take on the help of a therapist, because she's smart enough to say, 'If I don't have the tools, I'm going to seek out other people to help me find the tools to take control of this.'" 
 
On a lighter note, Katic addresses the question of whether or not Beckett and Castle, once they finally admit their feelings to one another, have the right stuff to go the distance. "I think Castle has more gravitas than we've seen," Katic says. "As the show continues, we'll see the other stuff that we haven't yet. We've seen lighter sides to her as well, so they're bringing balance to one another. All that matters in the end is they love each other and decide to commit to a relationship. They're at opposite ends, which I think can be a good thing, and I do think what they have what it takes to go the long haul."