LOS ANGELES — What happens after you save the world?

That’s not a quandary most actresses face. But if you are Sarah Michelle Gellar, it’s a real question. Having stepped into the lead role of “Buffy the Vampire Slayer” as a teenager, she found herself a cult icon by the time the series ended in 2003. The show’s influence lingered, with academics writing papers about its slang, its mythology, even its military strategies.

Gellar seemed unable to shake Buffy’s wise and wisecracking shadow for many years, flitting through a series of indie films and horror movies. When she took time off to have a baby with husband Freddie Prinze Jr. in 2009, fans began to wonder if she’d ever return.

And yet here she is, a petite 34-year-old woman dressed in a silky brown jumpsuit with a plunging neckline. She’s sitting in her trailer on the set of her new series, “Ringer,” which premieres Tuesday on the CW. It’s a long way from the Hellmouth.

Not only is Gellar co-executive producing this upscale thriller, she’s also playing the two central roles: Bridget, an ex-stripper on the run after witnessing a murder, and Siobahn, Bridget’s socialite twin sister, who is in so much trouble she’s prepared to fake her own death and let Bridget step into her own shoes.

“The joke is that I’m playing five characters,” Gellar explains. “I play Siobahn and Bridget present day, both women in flashback, and then ‘Shivette,’ which is when Bridget is pretending to be Siobahn.”

None of which quite squares with Gellar’s professed desire to make her life more manageable.

“Playing twins — you don’t think I took the easy route?” she asks sarcastically. Gellar says that producing her own show was crucial, allowing her to have control over as many elements of her life as possible. She takes naps during her lunch break so she can get up early with 1-year-old Charlotte, and she gleefully proclaims that Pottery Barn is designing an on-set nursery for cast and crew, because a child-friendly workplace matters to her.

“My family comes first, and you have to be in charge to be able to protect that. You have to be the one who says no or you don’t have a life, which is what I found out the first time,” she says, pulling off Siobahn’s high heels and curling her feet under her.

“She’s very savvy about a lot of things, let’s be clear,” says “Ringer” showrunner Pam Veasey, who also produces “CSI: NY.” “We’re of the same rhythm; we understand how to solve problems. She’s very smart about what we accomplish in a day.”

Gellar has surrounded herself with familiar faces from her “Buffy” years (caterers, costume, hair and makeup people) as well as Veasey and series creators Nicole Snyder and Eric Charmelo, who understand the demands of parenthood. “Our kids are all the same age. It’s a big support system I never had before.”

She says she joined a mommy group after her daughter was born and was the last woman to return to work. “I was trying to be supportive of everyone else, and I thought I was doing a good job — and then I went back to work and realized how hard it was! I literally wrote them all apologies saying, ‘Oh, my God, I didn’t realize!’” she squeals.

“I don’t want to feel like a failure to my daughter. She’s the best thing I’ve ever done. Buffy — pretty great and all, but Charlotte’s way better.”

Joss Whedon, the creator of “Buffy the Vampire Slayer,” says Gellar was always extremely ambitious and focused. “She was such a precision instrument. The control she applied to every syllable was incredible,” he says. “The downside to control is trying to get energy out of her. She used to say, ‘I can cry any time, but don’t ask me to laugh.’” Whedon says one of her nicknames on the set was “Jimmy Stewart” because “she suffered so well — you could turn the screws and the audience went with her.”

She was, even at 19, “the oldest pro I knew,” Whedon says.

‘Ringer’

When: 9 p.m. Tuesday

Channel: The CW