Grey's Anatomy returns next Thursday. "Don't Deceive Me (Please Don't Go)" marks the first appearance by Rachael Taylor and the directorial debut of Kevin McKidd.

Derek breaks ground on his clinical trial, but Meredith can't help but feel left out, while Bailey's attempt to integrate social media into Seattle Grace life irks Richard.

The story everyone's talking about, though, is the baby. Callie's expecting, she's keeping it, and what was a secret is about to be out in the open. Here's the promo:

Needless to say, things are going to get complicated. A minute-long sneak peek, which we've posted after the jump, sheds more light on how Mark reacts when he finds out.

You have to watch the clip to fully appreciate it, but to sum up, he thinks it's great, then briefly contemplates marriage, then after Callie shoots that down, realizes she's right.

He's in love with Lexie, after all. Oh crap, what am I going to tell Lexie?!

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.