Stana Katic on "Castle"

Credit: ABC

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."