ER: Season 8, Episode 18

8 - 18: Orion in the Sky

Mark serves his final day in the ER overseeing the first day of Gregory Pratt, a cocky yet eager new intern. Through observing his patients, he decides to forego chemotherapy, and spend his remaining days in peace. He also meets with his ex-wife, tells Weaver to live a little and leaves, never to return. Meanwhile, Abby plans to move back into her apartment when her landlord lets her know that Brian's moved out.