Seattle Grace is dealt a serious blow when it falls to a twelfth ranking among teaching hospitals. Richard takes the ranking personally and has no time for Erica when she asks for tips to improve her teaching skills.
Now that Meredith and Derek are back together, she keeps dreaming that he's dead. She decides to ask to move in with her and he accepts. His ex, Rose, is now hostile towards him, even in the OR. Derek asks her to transfer to another department but she insists on staying put.
It's snowing, but now that Seattle Grace's ranking has slipped, ambulances are taking accident victims to other hospitals. The residents are just about to give up on patient arrivals when a battered limo drives up: Three women on their way to a formal event have gotten into an accident which seriously wounded their driver. One of the women, Betty, appears to have a concussion since she keeps asking where she is. Sarah Beth and Anna are not seriously hurt, but are concerned about their husbands.
Miranda hears that a limo with three men -- the women's husbands -- is on its way to another hospital, so she informs the women they can ask for the men to be taken to Seattle Grace instead. When the men arrive, they're accompanied by Major Hunt, a military doctor who performed triage on the scene including using a pen for a tracheotomy. Hunt is hurt himself, but insists on checking on "his" patients. Cristina is impressed when he suggests a radical freezing technique to save Philip, who will be paralyzed otherwise. She's even more impressed when Hunt staples shut his own wound without any local anesthesia.
Sarah Beth doesn't know what to do when she's told that her husband's insurance expires at midnight and that all his credit cards have been canceled. Anna confesses to Meredith that she's been having an affair with Sarah Beth's husband.
Alex insists he's fineand Izzie tells him she still expects to see Denny around the corner, so it's okay if he needs some time to get over Ava. He regrets having broken down in front of her, however, and orders her to leave him alone.
Lexie scolds Sloan for being mean to George and the surgeon correctly guesses that she has a crush on George. He says he'll stop being cruel to George if she'll confess how she feels, but she refuses. George misunderstands the situation and thinks that Lexie is sleeping with Sloan.
Meredith has been talking Cristina's ear off about her anxieties over having Derek move in and finally Cristina snaps and yells at her to shut up, saying that the whole thing is a terrible idea. Cristina slips on some ice outside and before Meredith can help her up, a sharp icicle falls, stabbing Cristina in the chest.
Episode 502
Major Hunt comes to the rescue, carrying the injured Cristina inside. He instructs her not to remove the icicle until they've determined the extent of the damage and Richard agrees. Hunt is also on hand to read her X-ray and determine that it's finally safe to remove the icicle. He tells Cristina she'd make an excellent field doctor and advises her that although she lost a patient today, she won't make the same mistake again, which means she'll save the next person's life.
Because of the "woman cheating with her best friend's husband" patient situation, Meredith rethinks having Derek move in. He's not surprised and says he's willing to take baby steps with her. Rose accidentally hands Derek the wrong end of a scalpel during surgery, cutting his hand. She transfers to another department, rather than be the "Fatal Attraction" nurse.
Anna tells Meredith that Sarah Beth doesn't know that eight months ago her husband lost his job and that's when the affair began. Meredith advises Anna, as Sarah Beth's best friend, to tell her the truth, no matter how ugly it is.
Callie does some research and thinks they can pull off the freezing procedure Hunt mentioned. Derek is convinced it's more likely to kill the patient and tells Richard he's only given it the green light because he's desperate to boost the hospital's status.
The freezing process is going well but then Callie realizes that the patient's body temperature is too low. She panics and doesn't know what to do, but Erica tells her to stay calm and together they manage to save the patient. The procedure is a success and the man's mobility is restored.
Michael will never talk again, so he writes a letter to Sarah Beth that Lexie reads for him. He swears he still loves her and begs for forgiveness. Sarah Beth tells Alex she doesn't care if they operate on Michael before the midnight deadline or not. She asks him why men cheat and he answers maybe it's because they can't stand to be seen as weak. It's long after midnight before Miranda is available to operate on Michael, but she insists that Alex turn the clock back so the official time is a few minutes before the deadline.
Pre-surgery, Betty's memory kept resetting every 30 seconds and after she wakes, Izzie watches the clock to see how she does. Her friends are devastated when she keeps asking the same questions over and over, meaning her brain damage is permanent. Sobered by the losses of the day, Sarah Beth decides to forgive both her husband and best friend
Callie and Erica had been avoiding each other ever since their hookup, but now they decide to give their relationship a go, even though neither has ever been with another woman before.
Richard offers Hunt a job at the hospital, but he turns him down as he's due back on the front. Before he leaves, Hunt seizes the moment and kisses Cristina.
Meredith tells Cristina that she needs her to support her relationship with Derek because if she doesn't, then it really is doomed. Cristina assures her that she's still "her person" and that she thinks she and Derek will work.
Lexie tries to tell George how she feels, but when he says he considers her his best friend, and about sleeping with Meredith when he loved her and she didn't love him, Lexie holds her tongue.
When Izzie sees Alex with a half-naked woman at the house, she retreats into a fantasy in which she's reunited with Denny.
Richard informs the staff that they've all been resting on their laurels and that from now on, they're all going to have to try a lot harder.