ER: Season 9, Episode 1

9 - 1: Chaos Theory

Abby, Carter, Chen, Pratt, and Stan will be confined to the ER for two weeks, while all of the other patients are evacuated and sent to different hospitals. While on the roof arguing with Luka about the use of a helicopter, Romano backs up into the tail rotor, and has his arm severed above the elbow. Anspaugh arrives to perform surgery, and reattaches the arm. Susan is stuck on the roof with a dying patient. After 2 weeks, the ER reopens. While all of this has been going on, Elizabeth has been in London, working at her father's hospital, where her supervisor doesn't like the American mannerisms and vocabulary she's picked up. She ultimately decides to return to Chicago.