Colors
performed by Amos Lee

When David rented his quaint San Francisco apartment, the last thing he expected - or wanted -was a roommate. He starts to get settled in to his new place, which has become quite messy, when a woman named Elizabeth suddenly appears, insisting that the apartment is hers. David assumes there must have been some kind of misunderstanding, until Elizabeth disappears just as mysteriously as she appeared. David changes the locks, but this doesn't stop Elizabeth from appearing inside the apartment, mostly to chide David about his messy bachelor lifestyle. David is convinced that Elizabeth is a ghost and sets out to help her move to the "other side". Elizabeth realizes that she is not in fact dead, and is determined to resist David's efforts to help her cross over. Elizabeth and David work together to try to figure out who she really is and how she came to be in her present state. During this process, the two fall in love.

George and Derek work together, Denny still doesn't have a heart, and Meredith gets paired with Callie. A 12-week pregnant girl dies in the O.R. and her parents try to keep the baby alive. This causes tension between Derek and Addison. One doctor's overreaction unites two bickering patients. Finn is still treating Doc for medical problems. [edit] Expanded overview A shooting at a nearby restaurant bombards the hospital with plenty of gunshot victims -- and one intended victim that didn't get shot, but is a pain to everyone nonetheless. Burke is still mad at Christina, and he lets Alex go with him to retrieve a heart and not her. Cristina winds up on the case of a couple where the boyfriend used his girlfriend as a shield during the shooting. When Izzie finds out that the heart is for Denny, she begs Bailey to be on the case, so she can tell Denny the good news and prep him. Meredith works with Callie on a victim who was shot in the leg. She uses the time with Callie to pick her brain about bone cancer in her dog, but Callie doesn't have time for any dog talk -- until George says he has a right to be mad at Meredith, but Callie doesn't. George and Derek attend to a victim left brain dead -- and pregnant. Derek seeks Addison's help in talking to the parents about their decision to use their daughter as an incubator, but Addison -- who is seething to find out that Derek and Meredith's strife extends from Meredith dating the vet -- explodes on Derek in full view of everyone. When the heart intended for Denny doesn't prove to be viable, Burke fights for a second heart that is supposed to go another patient in another hospital -- and it's a battle he's losing until Izzie decides to take matters into her own hands. As Burke races back to SGH to keep Izzie from stopping Denny's heart, both Burke and Denny wind up in critical situations.

House is confronted by Kalvin, a flamboyant homosexual man who demands treatment when other doctors diagnose him with AIDS, something he admits he does have. House begins making moves on Stacy using sensitive information on her relationship with Mark.

The interns are pulled into Dr. Webber's office for interrogation regarding the LVAD wire situation. None of them reveal the truth, protecting Izzie. Dr. Webber tells them all that they're off surgery, and they are to give his niece a prom. Burke finds a tremor in his right hand. Meredith and Derek make the decision to put Doc to sleep. Izzie accepts Denny's marriage proposal. During the prom, Derek and Meredith reunite in an exam room. The interns find Izzie lying in bed clinging to Denny, whose heart has stopped. Izzie leaves Seattle Grace, and on her way out confesses to Dr. Webber that she cut the LVAD wire and that she quits the program. Meredith remains torn on who she should follow: Derek or Finn.

Sarah and Amber are both attracted to Amber's teacher, while Crosby tries to have a romantic moment with Valerie, but because he can't leave Jabbar alone too long the moment doesn't turn out that well. Meanwhile Julia thinks about doing pro bono work, but she's sure that her boss will not approve it. While Adam really needs a break from everyone.