Returns: Thursday, April 10, at 10 pm/ET (NBC) Number of new episodes: 6 Where we left off: Abby came clean about being in rehab. Betina (Gina Ravera) asked boyfriend Pratt to commit. Gates and Sam flirted. What's next: Gates and Sam's courtship speeds up. Goran Visnjic (Luka) returns to wrap up his tempest-tossed story line with Tierney. "It's not a tragic ending," exec producer David Zabel says, but "there will be a shocking reveal." New doc on the block: New attending physician Simon Brenner (Aussie actor David Lyons) stirs things up with everyone, especially Pratt. Reveals Zabel: "He's very good-looking, dashing and a nasty piece of work." Watch video clips | Photos | More Returning Favorites coverage