21. 5x20 "No Good at Saying Sorry (One More Chance)" (OAD 4/30/09)
Meredith sticks up for an abused child and the chief is angry with her. Meredith tells Derek that he has to be on her side and he talks to the chief, who then talks to Meredith and says he is sorry that she was neglected as a child. He saw it happening and did nothing about it.
Lexie wants Mark to meet her father and he doesn't want to, but he goes to dinner with them.
Owen is very distant to Cristina and she confronts him. He says that he's working with a therapist because he loves her and he knows that he is no good for her so he is trying to do the right thing by keeping his distance.
Izzie's mom comes after Bailey calls her. Then Bailey lies and tells her that Izzie's scans are good so that she'll leave. Izzie goes into another surgery.
22. 5x21 "What a Difference a Day Makes" (OAD 5/07/09)
Izzie continues to plan every detail of the wedding that is set to take place that evening. Denny shows up and Izzie knows that means she has another tumor. They hook her up to a machine and wait for her to have another hallucination. When she does, Derek is able to see the tumor, but it is so small, he can't get it out. Bailey suggests that he give up his wedding day for Alex and Izzie.
Meredith asks which of them will be her maid of honer and Izzie says Cristina because Meredith needs to be Alex's best man. Halfway down the aisle, Izzie has to pause for breath and George gets up and escorts her the rest of the way.
Back at the hospital, Izzie tells Denny that it was a beautiful wedding.
23. 5x22 "Here's to Future Days" (OAD 5/14/09)
Owen decides that he is not done in Iraq and that is why he can't face stuff at home. He wants Cristina's support, but she says she doesn't want him to die and can't support him. Instead, he decides to stay and finally goes to see his mother.
Mark wants Lexie to move in with him, but she's not ready.
Meredith suggests she and Derek go to city hall the next day, and he agrees.
George enlists in the army.
Webber and Arizona are fighting over Bailey, each trying to woo her into their area of speciality.
Izzie has to decide whether to go with the treatment the cancer doctor wants her to do, or the surgery that Derek wants. She decides on the surgery, but signs a DNR.
24. 5x23 "Now or Never" (OAD 5/14/09)
Derek and Meredith had planned to go to city hall, but there is no time, so they get married over a Post-It note where Derek writes down their promises to each other.
Owen and Cristina get back together.
Izzie wakes up from surgery, but her memory resets every minute or so. Alex yells at her because he's frustrated with her memory and she remembers it. As he hugs her, she loses consciousness.
A John Doe comes in badly hurt after being dragged by a bus after pushing a woman out of the way. He finally gets the message to Meredith that he is George.
Izzie goes in the elevator in the dress she'd worn to the prom the night Denny died. The elevator opens to reveal George in his Army uniform. They smile at each other.