Cuddy and Wilson try to get House to hire a new team, but House insists he doesn't need one. When he finally agrees, he typically decides to do it his way. It involves taking on 40 applicants, assigning them numbers, and having them compete for the positions. During the course of a case discussion, House thinks he sees Chase walk past his office. Later, he thinks he sees a blond Cameron in the lobby. Later still, he glimpses Foreman in the hall. Wilson and Cuddy inform him that Chase and Cameron are engaged and working in Arizona, Foreman is in New York.
Chase blows that by actually speaking to House, forcing Wilson to admit that Chase and Cameron are indeed still working for Princeton-Plainsboro. Foreman is, however, working in New York, but thinking outside the box (and thus saving his patient's life) gets him fired. Trying to get another position turns frustrating. Foreman is getting a rep as a House-type maverick. Turning to Cuddy, she rehires him without any concessions, because the only one who would hire "House Lite" would be the one who hired "House Classic."
Foreman is paired back up with House. House discovers that one of the remaining applicants (13) carries the gene for Huntington's chorea. He tries to get her to test herself, but she'd rather not know. Cuddy pushes House to pick his final two from the four remaining. He hires Taub and Kutner, then Cuddy tells him to keep 13 so he won't have an all male team. (House plays Cuddy like a guitar!)
Somewhat later, House suspects Wilson is dating someone, which he denies. Stalking Wilson to a restaurant, he learns that his friend is dating Amber, one of his fired applicants he affectionately nicknamed "Cutthroat Bitch." After House realizes that Wilson is attracted to the same qualities in Amber that characterize House, he says, "Oh my God; you're sleeping with me!"
Of course, House tries to get Wilson to dump Amber. When this fails, House tries to work out a Sharing Wilson schedule with Amber. The first of the two part season ender is a brilliant episode involving House suffering a head injury in a huge bus crash and trying to recover lost memories leading to the identity of someone he saw during the crash that he feels is going to die. By the end of the episode House realizes the person who's dying is Amber. For some as yet unknown reason, she was on the bus with him when it crashed but was taken to another hospital as a Jane Doe.
The second part continues trying to piece together info of what House saw that could explain Amber's deteriorating condition. Unfortunately, what House saw Amber take (flu pills just before the crash) coupled with her crash-damaged kidneys make dialysis ineffective. She is going to die, and that can't be stopped. House slips into a coma from his head wound, and Amber dies in Wilson's arms.
While in a coma, House finds himself on a white bus with Amber. She is dressed in white and unhurt. House is in a white hospital gown, walks normally, and is pain free. He tells Amber he wants to stay on the bus with her, because he doesn't hurt. He doesn't want to go on being miserable and have his only friend Wilson hate him because she died. Amber tells him, "You can't always get what you want." Then she tells him to get off the bus.
House awakes from his coma with Cuddy holding his hand. 13 faces the truth, that she has Huntington's Disease. Wilson cries, alone in his apartment that he shared with Amber.
That catches you up through Season 4 (which was shortened due to the writers' strike.) I'll do Season 5 tomorrow, and you should be set for Season 6!