Meredith is ready for surgery and surprised to see that the Chief is scrubbed in, rather than reading a magazine in the corner. He tells her that this is her big day, so he's just taking precautions; she knows that this means he's a little worried she might kill the patient on her wedding day. She assures him it will be fine and he claims to know that, telling her to pretend he's not even there. But he makes it difficult when she asks for the scalpel and he jumps in to tell her how great she sounded when she asked for it. Kooky music tells us that this is only going to keep happening throughout the surgery.
Mark feels positively shoehorned into this episode -- everything feels organic and then suddenly there he is, seemingly worried about Derek and Meredith's future. He is bugging Callie again and asks if it's good that Derek doesn't talk about the future or whether or not they will make it. Callie doesn't get a chance to answer because Arizona comes back to try and continue their conversation from earlier. She thinks Callie can't be that tired if she's working in the ER on her day off, so Callie counters that she rallied. Arizona challenges that she's lying, so Callie tells her she loves the ER and can't get enough of it. Sigh. Welcome to yet another plot that wouldn't even be a story if this GROWN WOMAN would just SAY what is wrong in the first place. Mark suggests this route, but Callie tells him to suck it.
George walks in to where Hunt is working on a girl with blue hair. He holds his head high and doesn't whine or cry, but does say that all of his patients are dying and Hunt needs to pull him. Hunt won't do it, saying that it's his decision, and instead sends George to meet another ambulance. George doesn't budge and pleads, "I'm in over my head." Hunt just orders him to walk away, and Lexie comes in at that moment to recognize and remind us that the one with the blue hair is Michelle.
Izzie, Bailey and Derek are looking at the scans from the MRI, and they are totally clean. Izzie's not satisfied, though, given the reappearance of her dead fiancée, and Derek has to admit he doesn't know why she's seeing him again. But Izzie points out how badly she wants to go to the perfect wedding that she planned, so why would she tell them about Denny if it wasn't true? The girl has a good point. She tells them that all this can mean is that there's something in the brain, causing Bailey to say oh-so-casually, "It's not like we can just map the brain for hallucinations the way we do with seizures..." But wait just a second there, you've got the world's most brilliant, gorgeous, fluffy-haired neurosurgeon sitting at the same table! Derek of course has an idea, given that hallucinations are neurons firing -- it's never been done before but if they can induce a hallucination they could maybe pick it up on an EKG and figure out where it is! Yes, ladies and gentlemen, this simple solution has up until now gone undiscovered because Derek Freaking Shepherd hadn't yet taken the five seconds it just took to come up with it. He is THAT GOOD.