Grey's Anatomy: Season 6, Episode 4

6 - 4: Tainted Obligation

Meredith and Lexie are crossed with one another when Thatcher arrives, in dire need of a liver transplant, and Meredith is the only one who is viable to do so. Mark is tired of Cristina's competitive zeal so he puts her on a case involving a man desiring a penis enlargement, and Izzie sympathizes with a man dying from cancer.