Look out, Addison’s back at Seattle Grace. But it’s only temporary. She's in town because her brother, Archer, needs help from the best neurosurgeon she knows. Of course, said neurosurgeon just happens to be her McDreamy ex-husband.
Archer has parasites in his brain. We know. It’s gross. They’re living in little sacks of fluid. It’s just about impossible to remove the sacks without puncturing them. Doing so would send all the little worms scurrying into Archer’s brain. Told ya it was gross.
And at first, Derek doesn’t think Archer’s case is operable. Sam, one of the other doctor’s from Oceanside Wellness, comes up with the idea of suctioning the sacks to drain them before removing them. Derek thinks it might work. It’s also Archer’s only shot. The surgery is a success and Derek is a hero.
Owen and Cristina treat a man who’s hiding his cancer from his daughter, Beth. Oh, and Beth just happens to be Owen’s ex-fiancée. Beth is shocked when she sees Owen. She thought he was still in Iraq.
We know what you’re thinking. Owen was engaged? That’s news to us. It’s news to Cristina, too. She realizes there’s a lot she doesn’t know about Owen. What kind of guy breaks up with his fiancée in a two-line email? And what kind of guy doesn’t tell his mom he’s back from war? We always thought Alex was a complex guy. But Owen blows him away!
Izzie creates a series of challenges to help her interns get their medical groove back. Lexie does well but George notices Sadie lagging behind. George tells her she has to let the Chief know she’s in over her head before she hurts someone.
Sadie admits to Meredith she cheated on her entrance exam. She quits the program at Seattle Grace and asks Meredith to go to Europe with her to relive their glory days. We know that’s just not going to happen. Meredith says, “I don’t want to sleep my way through Europe anymore. I want to be here.” We want you here too, Mer.
A pregnant patient named Jen has an aneurysm. Her surgery is delayed because of the emergency with Addison’s brother. She begs Derek to do the surgery tonight. She doesn’t want to wait until morning. Derek operates. After acing all of Izzie’s challenges, Lexie gets the grand prize of scrubbing in on the craniotomy. There's a complication during the surgery. But with Lexie's help, Derek fixes the problem.
At Joe’s, Derek walks in to loud cheers. "You were a god, today. You slew dragons and you walked on water," Addison tells him. Surrounded by their old friends, they sing a song that Derek composed for Addison. It’s little things like this that have Meredith thinking there’s a side to Derek she doesn’t know at all.
Back at the hospital, the pregnant aneurysm patient starts seizing. Alex yells, "Page Shepherd. Now!"