This episode fills in many of the blanks between the crash in last season's finale and Mark's death in the season premiere. It sounds like they were out in the woods for about four days and no one is doing well when they are brought to a hospital in Idaho, but Mere fares the best of everyone. Richard, Owen and Bailey immediately fly up to the hospital to meet them, and Bailey brings Zola which thankfully seems to bring Mere down from the brink of panic. She's the first of the survivors to heal, at least medically. Eventually they have to be transported via plane back to Seattle and Meredith orders Bailey to sedate them all so that they don't have to have any memory of taking another flight.

Derek is doing pretty well except for his crushed hand. The doctor working on him guarantees that he can get him back to at least 80% function and for a moment he tries to talk himself into a life of teaching and consulting because he realizes he's lucky to even be alive. But Callie proposes another procedure that is more risky but could potentially restore all his functionality, and he wants her to be the one to do it. She has no interest in taking on that responsibility, but he talks her into it. He and Mere also have a big fight about whether or not to move to Boston; he still wants to do it and thinks it's an important start to her career but she thinks they have too much going on in Seattle (not to mention his unknown surgical future) and it appears that she has won the fight, at least for now.

Cristina winds up with a form of psychosis and when Owen gets to her, she's been restrained to the bed because she kept attacking the doctors. He manages to calm her down but she then just goes blank and doesn't talk or do anything but lay in bed and stare for what seems to be days or weeks. When she finally gets home, Owen gives her a bath and she begins speaking about what happened: she didn't sleep for four days, did all she could to keep Mark alive when he kept almost dying, cleaned the bugs out of Arizona's leg, and tried to keep the animals away from Lexie's body though eventually she couldn't fully do that. (Ew.) When she finally gets back to sort of being herself, she flees as fast as she can for Minnesota (via car) and gets in a big fight with Mere before she goes. (They make up.)

When they get Mark back to Seattle, he's in really bad shape and it's looking like he really might die. He finally comes to and seems totally fine, but Richard suspects this is a "surge" -- terminal patients often will have a burst of energy, experience epiphanies, and deliver a lot of lessons and heartfelt declarations to those close to them. Mark seems to suspect it too and he goes over all of his medical directives with Richard which is where his 30-day life support instructions come from. Avery seems to realize as well about the surge but he hangs out with Mark, goes over cases with him, and generally just acts like everything is okay. When Mark tells him to convince a patient with small breasts that she's beautiful just the way she is, he know that this is likely the beginning of the end. He goes to get Sofia to sneak her in to see Mark and on his way runs into April, whose contract ran out and who is on her way home. He tells her to wait for him at Joe's so they can talk before she leaves, but she just gets on a plane back to the farm. When Avery returns with Sofia, Mark has crashed and that marks the beginning of the 30-day countdown.

Callie really has the worst of it because she's not sure if either her best friend or her wife are going to ultimately survive, and she's got to do a risky surgery on Derek to boot. At one point when she is sitting with Arizona Alex finally builds up the courage to come say hello and to tell her how one of their patients is doing. He tells Arizona that he would give anything to trade places with her and she lets him have it: wishing the exact same thing, blaming everything that happened on his being selfish, and calling him a horrible person who deserved all of this tragedy when she did not. She's desperately afraid of losing her leg and is sure that Callie can come up with a plan that will fix it for her; finally she begs Callie to promise that they won't cut it off and though she seems unsure, Callie makes that promise.

Unfortunately, the infection is really bad, and Callie has to fight with Owen to get him to consider any treatment other than amputation (though even then, she'd likely be facing limited use and constant pain). Callie finally breaks down and admits that the Arizona she knows seems to be gone, and she's sure that if they amputate the leg, she'll never get her wife back again. This gets to Owen, so he agrees to continue with various other treatments for now. While Callie is operating on Derek's hand, Alex goes back to Arizona's room to say goodbye before leaving for Hopkins. As he's talking, though, Arizona starts to crash. He runs into the OR (just at a super crucial part of the surgery involving Derek's nerves, of course) to tell Callie and she completely panics but finally realizes that the leg is killing Arizona. She tells Alex to cut it off, and please do a good job. So this brings us full circle although it throws one more interesting twist into the drama: Arizona is livid with Callie for cutting her leg off but it turns out it was Alex who did it, and Callie is taking the heat because God only knows how Arizona would fall apart if she found out that Alex was responsible for this injustice too.