Criminal Minds Stars Tease Season 8 Finale's Big Death: "I've Never Hated an Episode More!"

"One of us is in jeopardy, but if you do the math and go in the Internet you're going to see who signed deals and who didn't," Shemar Moore explains of the CBS hit's fatality

"It's my least favorite episode ever."

Tell us how you really feel, Kirsten Vangsness! Criminal Minds' season-eight finale airs tonight and let's just say something major goes down. Like, one of our beloved characters dying kind of major. It's a death so upsetting that Vangsness tells us, "I've never hated an episode more than this and I think we should all not watch it and then they'll have to rewrite it and make history different. I hate it that much."

So who's dying? And what was it like working with Star Wars legend Mark Hamill, who guest stars in the finale? We caught up with Vangsness and Shemar Moore to get scoop on the season eight finale, and find out what's in store next season!

"One of us is in jeopardy, but if you do the math and go in the Internet you're going to see who signed deals and who didn't! [Laughs.] So if you signed a deal, it must mean you're alright," Moore teases of two-hour finale. "It's action-packed, it's fun, it moves along and it's intense. Somebody that the fans know fairly well but least expect is up against it."

Silver lining? There's no major cliffhanger to spend the summer fretting over, as Moore reveals, "After all the explosions and stuff, there's a nice calm, a nice calm with the remaining team."

Aside from the death, explosions and calm, fans can expect to see Hamill make a "creepy" turn in the finale, though Moore tells us the actor was "charming" and guest-starred on the show after a nudge from his daughter. "His daughter is a huge fan of the show, so Matthew Gray Gubler and I were arguing over who she liked more! She's like, ‘No, I did it because of Joe [Mantegna]!'"

Criminal Minds' finale airs tonight at 9 p.m. on CBS.