How is Mark feeling after doing the deed with Lexie - and will he go down that road again? Will the doctors' ethics remain intact when they must treat a serial killer? Does Dr. Bailey have a new threat to her authority as Chief Resident? Is George out, or staying put?

And finally, how does Alex react when Izzie first tells him about her recurring visions of Denny Duquette? The answer to that one may really surprise you ...

[video url="http://www.greysanatomyinsider.com/videos/wish-you-were-here-sneak-preview-4/" title="Wish You Were Here Sneak Preview #4"][/video]

Read all about it, and check out five more previews of Thursday's all-new episode of the medical drama, via our inside source for Grey's Anatomy spoilers!

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