Cristina's looking at the surgical board that broke her heart. She tells Bailey that Hahn's job is to teach and that she can't just do this. "So make her teach me." Bailey just shrugs and replies, "If the chemistry isn't there..." I think Cristina has a point about it being a job and not just a whim, but as I've pointed out a million times before, we shouldn't focus on the questionable practices of Seattle Grace. Cristina thinks Hahn just doesn't like her, but Bailey points out that Hahn says it's a chemistry thing. Apparently she said this off-screen, since we never saw anything other than that she just doesn't like Cristina. Cristina goes to find Callie, but Bailey catches her and says that Callie told Bailey to tell Cristina (phew) that she should find another specialty. Cristina's shocked, but Bailey just tells her that it's not working with Hahn, so she should make it work with another field, and suggests the ER. Cristina wants to protest, but Bailey tells her it's an order and not a request, adding belatedly, "From your Chief Resident."
Actually taking advice for once, Cristina dejectedly leads her interns (hey, they're back this week!) to the ER, and for exposition purposes tells them that it can be a "candy store" of things like car crashes and impalements. Remind me never to move to Seattle if getting impaled isn't uncommon. She asks the nurse what they've got, and the little life left in her seeps out when she hears it's a sprained ankle and an infected bunion. She tells the interns, "It can also strip you of your will to live." She then orders them to troll and find her something good. Lexie still hasn't shown herself to be too good at following directions, and instead of leaving she goes up to Cristina to ask if Meredith said anything about her, since Mere's been avoiding her "for days." If you already feel like your resident hates you, continuing to ask her personal questions about her best friend when she clearly hates that isn't going to end well. And it doesn't, but as Cristina starts to tell her off, a hysterical woman bursts through the doors carrying an infant. She fell down, and the baby hit her head and then stopped crying on the way over. She's too terrified to give the baby to anyone, instead begging Cristina or anyone to promise her that the baby will be okay. "You don't die from falling down the stairs, right?" Oh no, ma'am, you never should ask that rhetorical question in an ER; it never ends well. Cristina finally convinces her to hand over the baby. After a quick look she orders Lexie to take her and page Derek, and the relieved mother grabs her in a hug and won't let go. However, she then collapses, unconscious, and Cristina calls for a crash cart over the title card.
Cristina is working on the mother and as she puts in a tube, blood gushes out of the mother's chest. Hahn and Meredith file in and Cristina explains that her name is Teresa Brotherton (apparently Cristina can add "psychic" before "Dr." on her business cards, because Teresa never told her that before she passed out) and explains she used a needle for a tension pneumo. Because someone on the writing staff clearly wants me to have to recap collapsed lungs as much as possible since it's so fun to relive. In response Hahn makes some assessments and asks if she can feel that, but when Cristina puts her hand in, Hahn snaps that she was talking to Meredith. It's a little passive-aggressive for a woman who's supposed to be so ballsy and awesome, not to mention a little bit one-note already since I can't figure out a good reason why she'd hate Cristina so much. Especially when you consider that she once complimented Cristina for being like her when she was younger. Regardless, Hahn dismisses Cristina, and although Meredith looks kind of awkward after viewing the exchange, she goes in and takes over.