Julianna Margulies wasn't sure she'd return for ER's series finale.
"I said from the beginning I would come back if George came back," she tells TV Guide. "But I was pretty sure George wasn't going to come back."
"I said, 'If you do it, I'll do it,' and he said, 'Well, if you do it, I'll do it!'" she says.
Once she returned to the set, "It felt as though a lifetime had happened since then ... and nothing had happened since then," she says. "Half the crew is still there, God bless them. We were all family. It was like coming home."
She says she and Clooney wanted to keep their return "quiet because neither George nor I wanted to sit on talk shows, getting people to watch the final
episode of ER. It's the last thing George needs."
"Of course, the day we get there, I could see a long lens outside the Warner Bros gate taking pictures of us walking to the set," she adds. "Nothing's sacred anymore."
Margulies -- who played Nurse Carol Hathaway -- says she worked with Clooney -- who played her love interest, Dr. Doug Ross -- for "two days and we had
an amazing time."
Their storyline is "not sensationalistic. John [Wells, executive producer] stayed true to what my feeling was about the characters."
"You pick up a slice of their life now," she says. "It's very satisfying."
Spoiler! The couple has twin girls, now in fourth grade.
Says Margulies, "That could be a whole other show."
The finale airs on NBC in April.