Dr. Addison Montgomery is back at Seattle Grace.
Or, more accurately, she's dancing in a bar near her old stomping grounds. She has reason to celebrate. Her old boyfriend, Dr. Derek 'McDreamy' Shepherd, just saved her brother Archer's life by removing a sack of parasites from his brain. Derek is also at the bar, but he dashes out. Fearing that Archer may be in trouble, Addison, Naomi and Sam run after him.
No, Archer is fine. Derek is busy with another patient, Jen, a pregnant woman who has just come out of surgery and can't breathe. And Derek can't figure out why. But, he's smart. We have faith in him.