Mekhi Phifer makes his first series appearance as Gregory Pratt, a remarkably self-confident intern who is supervised by Greene (Anthony Edwards) during the latter's last day with the ER. Pratt's zealous eagerness prompts the terminally ill Greene to rethink how he will spend his final days on earth; and later on, he has a poignant reunion with his ex-wife, Jenn (Christine Harnos). Elsewhere, Abby (Maura Tierney) finally feels safe enough to return to her own home. ~ Hal Erickson, Rovi