Meredith and Cristina are still fighting, but Bailey doesn't care and assigns them both to help Derek and Owen on a special assignment from the Chief. When they get to the trauma center, they find out that their special project is a death-row inmate that was beaten and stabbed.
The doctors don't really know much about him, other than he's a death-row inmate, but that's enough for Cristina and Derek to be immediately hostile and Derek to refuse morphine even after discovering a toothbrush-shiv in the patient's spine. Meredith gives the prisoner morphine anyway. When Cristina finally gets the inmate to tell her and Meredith what he did, he describes giving in to his urge to slit a woman's throat and liking it so much that he killed two women the next day and two more the day after that.
Sadie mentions to Meredith that they had a fight like this before and their friendship never really recovered as proof that Meredith needs to try to patch things up with Cristina, "Deth" brushes her off by haughtily saying that she apologized.
Owen spends the night alternating between pushing Cristina away and trying to be her buddy. Cristina finally tells him that she just can't handle his hot and cold routine tonight, and tells him to just leave her the hell alone. We later find out from Derek that much of his hostility towards the shivved inmate comes from his father being murdered by two robbers when he was younger. Derek then steps up his occasional coolness by offering to do whatever Cristina would do to make Meredith feel better. Cristina tells him that Cristina would probably crank up the music and "dance it out" with her, which she doubts Derek's up to, but Derek steps up and starts dancing, making Meredith get up and join him.
Sloane starts out the evening by regretting sleeping with Lexie. He tells her that he made his best friend one promise and he slipped up, but it can't happen again. Callie's still lusting after Sadie, so they decide to form a support group to keep each-other from slipping up and succumbing to temptation.
Unfortunately, George makes this more difficult when he pulls all four in to help him with the case of a woman with incredibly frail bones. After some tests, they determine that a benign tumor has been leeching away her calcium, thus making her prone to breaks. She lapses into a funny routine of continuously screaming at the sky as someone to blame for her bad luck. Through her repeated frustrations, it becomes clear that she passed up moving to Denver with the love of her life because there's ice in Colorado is prone to broken bones. Her surgery is a success and her first question is how soon she can leave so she can move to Denver.
Sloane and Callie continue to try to support each other's resolve in the bar, but Sloane finally gives in, decides that you only live once, and tells Callie that he's "going to Denver". Callie continues to hold out for now.
Bailey and Alex are helping on the case of a boy suffering from serious kidney problems. Bailey's possessed by the exposition fairy and explains to Alex that she and the pediatric surgeon heading up the case have been working with the family for years and it's a very special case. Alex helps the surgeon examine the boy while Bailey talks to his mom. As they're talking to the boy, the head surgeon drops dead from a heart attack.
When Bailey tells the Chief about this, the Chief refuses to talk and locks himself in a room with a "Do Not Disturb" sign on the door. He later reveals that he's afraid for the life of the hospital. He can't find anyone to be the head of Pediatric Surgery, he can't keep a Cardiac Surgeon, and the interns are cutting each-other up. He confesses that he feels like he's failed at his mission of the past however-many years.
A new pediatric surgeon is assigned to pick up the dead doctor's cases and rubs Bailey the wrong way when she suggests that the wrong methods have been used on the boy up until now. Bailey tries to complain to the chief, but he points out that she hasn't liked any of the attendings at first and tells her just to deal with it. Eventually, Bailey realizes that just because the new surgeon is young and new to the case doesn't mean she doesn't know what she's talking about and begins working with her to get a transplant for the boy.
Alex refuses to sign the boy's application to "The Wish People" because that would mean the boy is dying. Alex insists that he's just sick and he wouldn't want to go to the rodeo anyway - they smell like horse crap. Eventually, once the boy is put on the transplant list, Alex sits down with him to pick out wishes.
Izzie finally decides to fess up to Alex and tell him what's been going on with Denny. At first, he just thinks she's dreaming about Denny and blows it off. Later, she corners him and tries to stress just how deep this goes, but he still isn't really fazed.
It's Izzie's birthday and Alex bakes her a cake. He warns her that the cake tastes pretty crappy, but the icing's good. Izzie starts to make a wish, but says she has everything she'd wish for. Alex tells her just to wish for nothing to change, ever. She smiles at Alex and Denny and blows out the candle.