Grey's Anatomy season 4 caught us up with our doctors after they'd been on vacation for 17 days. The interns return as first year residents, except for George, who has to repeat his intern year. Each of the residents is assigned interns. Cristina has Lexie Grey, Meredith's half-sister, who desperately wants to get to know Meredith.
1. 4x1 "A Change Is Gonna Come" (OAD 9/27/07)
Derek tells Cristina that Burke put in his resignation two weeks prior. Derek talks to Meredith and she says that it's over, and then they have break up sex.
Izzie talks to George in the stairway saying that she told him she loved him and then she didn't hear from him for over two weeks. That night he comes to the house and tells her that he loves her too.
Bailey is upset that Callie was made chief resident and Webber tries to explain that it's because she is a great surgeon and belongs in the OR. He says she'll thank him for it one day and she says, "Not today."
Addison is gone and Mark wants to have a drink with Derek, but Derek won't.
2. 4x2 "Love/Addiction" (OAD 10/4/07)
George decides to tell Callie that their marriage is over, then Izzie asks him not to. Derek and Meredith are seeing each other only for sex and Derek decides to stop, but can't. Lexie keeps staring at Meredith and Meredith tells her that she doesn't want to know her. Burke's mother gets the key from Cristina and then gets the rest of Burke's stuff from the apartment.
Callie has a hard time running the residents and Bailey is upset that Callie won't give her a resident for the clinic, only interns. Bailey begs Meredith to help her and Meredith does.
3. 4x3 "Let the Truth Sting" (OAD 10/11/07)
Meredith feels sorry for Cristina, so she gives her a surgery and Meredith takes Cristina's interns, including Lexie. She tries to teach Lexie, but Lexie gets mad and Meredith sends her to the clinic. Bailey tells Meredith to talk to Lexie because her mother died and Meredith was Susan's doctor.
Bailey has a hard time with Callie being the chief resident and finally talks to her about it and says that they can be a team.
George tells Izzie that he will tell Callie on his own time. That night he tells Callie that he'd slept with Izzie.
Cristina figures out that Meredith is sleeping with Derek.
Really Old Guy wakes up and Izzie tries to save him, but he wants to die and finally does.
4. 4x4 "The Heart of the Matter" (OAD 10/18/07)
Izzie thinks Callie wants to beat her up and the rumor is started. Callie is offended that Izzie would think that. Alex is disgusted that Izzie slept with George and that she told him like he was one of her chick friends. Izzie cries at home.
Richard's niece is brought back into the hospital and she doesn't want any further measures to cure her cancer. Adele expects Richard to talk her into the treatments, but Richard says he'll do whatever his niece wants.
Meredith gets stuck with Norman, the elderly intern. He looks at the chart wrong and they tell a healthy patient that she is going to die.
Meredith tells Cristina that she hates the idea of Lexie, but the person herself isn't so bad.
5. 4x5 "Haunt You Every Day" (OAD 10/25/07)
Meredith dreams of her mother and feels she is being haunted, so she takes the urn out of her closet and puts her mother's ashes into a plastic bag and takes them to work. She wants to put her mother to rest, and ends up washing the ashes down the sink in the scrub room. Webber comes in and helps her.
When Izzie asks a question, Callie announces to everyone that Izzie slept with her husband. Izzie and George just try to make it through the day. Izzie apologizes to Cristina and tells her to cut Izzie some slack.
Cristina is looking for a roommate and tells Webber he can move in, but recants when he hires Erica Hahn as chief cardiothorasic surgeon after she'd judged Cristina for sleeping with Burke. Instead, she allows Callie to move in.
6. 4x6 "Kung Fu Fighting" (OAD 11/01/07)
Cristina spends the night with Meredith because of Meredith's nightmares. Meredith tells Cristina that she's not ready to give up that safe feeling that comes just after sex with Derek.
Callie tells George that she's letting it go and George an Izzie plan the perfect night together, only when the time comes Izzie starts to cry because she's so exhausted from work and she wants it to be perfect.
Dr. Webber invites Derek and Mark to a gentlemen's night, and Dr. Hahn is offended that she wasn't invited. He says she can come and the four end up playing monopoly.
Lexie goes home with Alex and sleeps with him, then is horrified to find out that he lives with Meredith who finds them together.
Hahn is keeping Cristina out of her surgeries.
7. 4x7 "Physical Attraction...Chemical Reaction" (OAD 11/08/07)
Izzie and George are distraught because they have no chemistry in bed despite several tries.
Callie asks Bailey to cover for her so that she can do some surgeries. Bailey does an excellent job and the chief gets suspicious. When he figures out what is going on, he fires Callie and makes Bailey the chief resident. She cries and hugs him.
Mark asks Erica Hahn out, but she won't date him because she's not attracted to him.
Meredith asks Alex to stay away from Lexie, but after Lexie talks to Meredith, Meredith asks him to take Lexie home. Once there, he discovers that their father is about to drive drunk. They stop him and Lexie asks Alex not to tell Meredith.
8. 4x8 "Forever Young" (OAD 11/15/07)
Drunk and with a bleeding hand, Thatcher comes into the hospital asking for Meredith. Meredith stitches her father's hand. He says he is proud of her and that he regrets everyday missing her life. After talking to Lexie, Meredith realizes that he didn't mean any of it.
Bailey loves her new job as chief resident. An old high school friend comes in and flirts with Bailey. Hahn tells her she's a blathering idiot. She soon figures out that the man is using her, just like he did in high school when she helped him with homework.
Izzie and George don't even speak to each other anymore and it gets around the hospital that they broke up, which makes Callie happy. That night they talk and say they don't want to lose their best friend.
9. 4x9 "Crash Into Me: Part 1" (OAD 11/22/07)
Two paramedics are trapped in an ambulance that was just hit by a second ambulance after the driver had a seizure. A paramedic needs care, but tries to hide his abdominal swastika from Bailey, then Webber, then Cristina. Bailey brings George in on the paramedic's insistence that a white doctor be present.
Meredith stays with the men in the first ambulance and realizes that Stan is going to bleed out as soon as they get him from the truck. He says his wife works in the hospital and Meredith gets her.
Mark has a patient whose carotid artery is covered by a light flap of skin after Mark removed a tumor. Lexie becomes friends with the patient and is talking to him about what a jerk Alex is. Suddenly, the artery bursts. Lexie freezes.
10. 4x10 "Crash Into Me: Part 2" (OAD 12/06/07)
Lexie tries to the stop the bleeding for the carotid artery that burst in her patient. Dr. Sloan comes in and they get the patient into surgery, but he dies.
Derek works closely with Rose during surgery and afterwards, they kiss. Later, not knowing that this happened, Meredith tells Derek that she doesn't want him seeing anyone else.
Rebecca returns and wants Alex to call her Ava, but he says she's playing dress up and needs to go back to her husband.
Bailey fights with her husband, who says she is never around.