George Clooney by George Pimentel/ WireImage.com George Clooney by George Pimentel/ WireImage.com

Is George Clooney planning a visit to the ER for the drama's final, star-studded season? The megastar's publicist says no - but when Dr. Ross returned in 2000 for the departure of Julianna Margulies' Carol Hathaway, the scene remained top secret until the day it aired.

Here's what's happening behind the scenes. On September 10, executive producer John Wells lunched on the Warner Bros. lot with original ER stars Anthony Edwards (Dr. Greene) and Noah Wyle (Dr. Carter). Edwards appears in flashbacks on the November 13 show, and Wyle pops up in four of the final episodes. So of ER's original six stars, that's two returns down, three to go. Sorry, Sherry Stringfield. I'm hearing that when you quit the show for the second time in 2005, that was Dr. Lewis' last appointment at County General.

Story lines have already been conceived to bring back Clooney, Margulies, and even Eriq La Salle (Dr. Benton), who hastily exited the series in 2001. Show runner/executive producer David Zabel says he's "optimistic that we might be able to get them all. We have a really good story line for every [major] character from the past to show [the actors] what we want to do." Wells is directly involved in the conversations with all past cast members.

Zabel, who wrote and directed Edwards' double-hankie flashbacks alongside new series regular Angela Bassett, believes, "It helps a lot that we're doing a great episode with Anthony. It shows that [returns] can be done in a way that's not just a swan-song wave to the audience, but rather compelling dramatic stories that are interesting for an actor to play."

That strategy has already hooked popular vets Laura Innes (Dr. Weaver) and Paul McCrane (Dr. Romano), who appear with Anthony in his flashbacks. Coming up: Alex Kingston will be invited to bring Dr. Corday back from England with daughter Ella in tow. And Dr. Greene's now-grown daughter, Rachel, is expected to reappear as a first-year med student. "We have a lot of interesting ways of reuniting past characters," teases Zabel. "Sometimes in surprising, accidental ways and sometimes in ways where they reach out to each other."

The series will flatline with a two-hour May finale preceded by a one-hour, star-filled retrospective. But don't expect the finale, penned by Wells, to feature all the docs back together at a wedding or a hospital gala. "We talked about that," says Zabel. "But one of our concerns was that might lend itself toward hokiness."

Paging Dr. Ross... - Will Keck

See Clooney talk about how he auditioned for ER at our Online Video Guide.