Taub tells House that he found a donor with a 5 out of 6 HLA match. House finds it suspicious that Maggie refused to let her daughter give marrow, but before he can think too much about it, Taub shoves a present into his hands. He's not quick enough, though, as Agnes rushes into the room, her Present Detector on high alert. Also, she's there to inform them that the CA2 test came back negative. Maggie won't need new bone marrow, but she will need a new coffin. Agnes takes a second to look sufficiently saddened by the news of their patient's death before spotting Taub's present in House's hands. Taub looks worried that he's about to get stepped on by Agnes, but instead, she pulls a present out of her folder and gives it to House. Then she asks who gets to give Maggie the great news. House wants to do it, because he loves giving gifts as much as he loves getting them. In fact, he even gives the Cottages a present: they get to spend Christmas Eve in the lab, finding out what's about to kill their patient. Taub and Agnes look pissed, but that's probably because they know Kumar is going to stick his CD of Cool Yule Christmas songs in the stereo and put it on loop.
The Cottages test away. Kumar groans that it doesn't matter what Maggie has, since it can't be cured. Idiot -- of course it matters! What if it's genetic? Don't you think Jane would like to know what killed her mother, especially if it could also kill her? But Kumar wants to talk about more important matters, and asks if everyone is mad at him for giving House a present even after he said he wouldn't. Agnes says she isn't mad at Kumar because she knows that's what House wants, and that if he doesn't get it, it'll drive him nuts. I still don't understand why she wanted to work for a guy she clearly hates, no matter how brilliant a doctor he is. Foreman scoffs that driving House nuts won't make their situations any better. And then Jane walks in, demanding that they test her marrow.
Meanwhile, House tells Maggie that she's dying and has "one last Christmas" with her daughter. And not even that, really, since it's January and Christmas is already over. House suggests making the most of the little time they have left by telling Jane that she's adopted. Oh, yeah, that's just the kind of thing an eleven-year-old wants to hear when she's struggling to accept her mother's impending death. House, of course, figured out Maggie's secret when she refused the marrow test for Jane because she knew it wouldn't match. House even threatens to do DNA tests if Maggie doesn't tell the truth, like, what does it matter? Maggie has a day to live, and you're going to ruin it with DNA tests, House? Just drop it. But Maggie admits that she never thought she'd have kids because she didn't want to pass down her cancery genes. Then she "met" a pregnant drug addict who didn't want to have an abortion. But she did want to do drugs while pregnant? Because if she could stop doing drugs while pregnant, why not just keep the baby and stay off the drugs? That doesn't really make sense. Maggie promised the woman that she would never tell Jane who her real mother was. House says that Jane will live a lie, and Maggie will die a hypocrite. But he'll be a happy man, since he finally caught Maggie in a lie. To me, it makes no sense that Maggie would be so into telling her daughter the truth about everything while also not telling her she was adopted. There's nothing stopping Maggie from telling Jane she's adopted but not revealing who her bliological mother is. She could have honestly told Jane that she promised her biological mother she would keep her secret. And then Maggie would never have lied to her daughter. It's just a plot device to prove that even Maggie would lie, and it's a flimsy one. Perhaps worse, it's yet another thing we've seen on this show before.