Chase apparently drew the short straw and is on Horrible News Delivering duty. He tells Dan and the family that they're not exactly sure that it's MS, but they're going to treat him for it. The family ask Chase what MS is, and he doesn't mince words as he explains that it's horrible and painful and incurable.
Night falls. A nurse enters Dan's room to clear his food tray, at which point she notices that he isn't there. Chase, Cameron, and Foreman are soon on the case, running around the hospital to find him. The Cottages seems to be at this hospital 24/7; don't they ever go home? House does. He's sitting around watching TV, two suspicious-looking "cigarettes" (I hear pot is good for people with pain problems) nearby, when his phone rings. He doesn't answer. His machine picks up: "I'm not here, leave a message" it grumps as an annoyed House starts to stand up, already knowing whom it's from and why, as he cleverly did some mental differential-diagnosing and eliminated the possibility of its being any friends wanting to hang out, for obvious reasons. Thus, it must be one of the Cottages.
House limps into the hospital just in time to see Cuddy leaving, wearing her tennis threads. Who wears a skirt to play non-competitive tennis these days? Cuddy! She's amazed to see House after hours. He explains that his hooker accidentally went to his office instead of his home, and limps off. Cuddy stands there, not sure which scenario is less likely: House dealing with a patient outside of working hours, or a hooker going to the wrong address.
House de-elevators and runs into Foreman, who informs him that Dan is missing, even though he was apparently the person who left the message for House in the first place. House wants to know why this couldn't have waited until the next morning, and turns to leave. Foreman asks House what he was supposed to do; House told them to call him if they needed anything, after all. House says that if there's something he can actually help with, they should call him. As it is, he's not so good at search parties or waiting around being worried, so he's useless here. Interesting wardrobe choice for House here, by the way: he's got a t-shirt with a graphic on it that I believe is for a band, although I can't get a good enough look at it to see which one. It's not what I would expect a guy in his mid-forties to wear, but then, House does a lot of things I wouldn't expect people of ANY age to do. As the elevator doors close, House suggests that they check the roof for Dan.