Ken Barnett

A mystery woman sabotages Barney's love life, and to try to figure out who she is, Barney creates his own set of tournament brackets to decide which of 64 women has the most cause to hate him.

Addison returns to Seattle Grace to perform an operation and is surprised by all the changes in the lives of her former co-workers; Derek and Meredith's clinical trial has its first patient; Rebecca returns with shocking news for Alex.

Ari receives Billy's script for Vince's next project, but Billy's interpretation is vastly different from the adaptation he was commissioned to write. While Ari scrambles to keep the studio interested in the project, Eric is busy managing some domestic issues between his new client and her needy boyfriend.