zzie couldn't be more thrilled when George promises he's going to tell Callie that the marriage is over. But after a day of working under Callie, she orders George not to say anything since Callie is her boss and it's going to be a nightmare when she finds out. Izzie hopes that maybe they'll just "drift apart." George reluctantly agrees to wait.
Derek stays the night with Meredith, which is okay if it's just sex, but not if it's a "sleepover." She turns him down for lunch, insisting they agreed only to "sex and mockery," and asks him to meet her after work for more of the same.
Instead of returning her wedding presents, Cristina is handing them out in exchange for professional favors at the hospital, like scrubbing in on a high-profile surgery with Mark. Mama Burke arrives unexpectedly, looking for her and Cristina sends Meredith to get her to leave. Mama reprimands Meredith for the way she announced that the marriage was off, so Meredith tells Cristina she tried but Mama's too scary.
Callie refuses to allow residents to go work at the clinic because the hospital is busy, so Miranda gets saddled with two inept interns, including Lexie. She doesn't have the authority to give Meredith orders anymore, but Miranda says Meredith owes her for saving her life. Meredith regrets helping out when Lexie immediately pounces on her for more sisterly bonding and Callie is furious when she learns that Miranda undermined her over the clinic assignment.
The victims of an apartment explosion flood Seattle Grace, including a baby that won't stop crying and his very distraught father. A tox scan of the baby's blood, ordered by a suspicious Alex, reveals the presence of crystal meth. The parents were cooking the drug in their kitchen when it blew up. Callie has Alex call the police and social services. Before they can arrive and deal with the dad, Alex tells the father, who's freaking out over his son's crying, that he's going to jail for endangering his son. The father knocks Alex out and takes the baby.
Richard is trying to delegate work to make more time to be with his wife, but he regrets delegating the meth lab situation to Callie. He interrupts a surgery to tell her how badly she's messed up. When Izzie tells her she thinks she's doing a good job as chief resident , Callie not only doesn't believe her, she orders her out of her O.R.
While Mama waits to see Cristina, George tells her maybe Burke dodged a bullet by not getting married, because once you're in, you're in. She advises him not to stay in a marriage just out of obligation. Derek stops by next and Mama asks if Cristina really loved Burke. He says he thinks she loved him the best she knew how, but confesses it wouldn't have been enough for him either. She tells him he's an "honorable man" if he knows when to walk away from less than he deserves.
Callie desperately searches for the baby and when Mark asks if she's okay, confides that she thinks that George is having an affair. He says if it's true, George is an idiot. He advises her to talk to George, instead of destroying her career.
Meredith, who's been fending off an obsessed Lexie all day, finally tells her to leave her alone, because she doesn't want to know her. When Lexie points out they have the same father Meredith says, no, they don't. Her father abandoned her when she was five and that's why she kicked the world's most perfect man out of her bed, because their father chose Lexie over her. "You're not a girl I ever wanted to have to know," she says.
Derek overhears the meth-dealing father, who's hiding in a bathroom, begging his baby to wake up. Derek takes the baby, who's had a stroke, and runs with it. While Alex and Miranda watch Derek operate, Alex invites Miranda to yell at him for letting this happen. She says it's not her job but then she unleashes an angry rant on him. He thanks her for the lecture and she thanks him for letting her give it.
Cristina finally goes to find out what Mama wants. She asks for the key to the apartment to get some of Burke's things. And she says she's sorry, not just that Cristina lost the man she loves, but that she lost her teacher, since Cristina loves being a surgeon more than she loved her son. She says she admires Cristina and that if she'd been born at a different time, she might have been more like her. As she's preparing to leave, Cristina asks if she'll take the wedding gifts. Cristina asks, "He's never coming back, is he? Not even to say goodbye," and Mama reminds her, "You're a strong woman."
Callie offers to help the Chief fill out the paperwork on the kidnapped baby, but he tells she's already done enough for one day. George finds her and is about to tell her about him and Izzie, but she tearfully begs him, "Not tonight."
Derek asks Mark to meet Meredith in his place and tell her he's stuck with a patient, but then he decides to join her after all. They walk out together, smiling.