Sarah Michelle Gellar is bringing double the trouble in her new CW series Ringer.

The iconic Buffy the Vampire Slayer star, 34, plays estranged twins Bridget, a recovering addict, and Siobhan, a Manhattan socialite, on the gripping new thriller.

In the clip above, Gellar (as Bridget) assumes her twin sister's identity following her mysterious disappearance. "I'm the only one that knows that she's dead. I saw a way out and I took it. . . I felt like I didn't have a choice," Bridget says. "They all think that I'm her. They all think I'm Siobhan."

After a small break from the spotlight, Gellar -- mom to 23-month-old Charlotte with husband Freddie Prinze Jr. -- says she was looking for something challenging.

"I get frustrated with shows that set up mysteries and don't give answers," Gellar recently told Us Weekly. "On Ringer, we'll give answers. We'll unravel why the two haven't seen each other in seven years, Bridget's motivation for redemption and why Siobhan feels wronged. The best parts of the reveals."

Ringer premieres September 13 at 9 p.m. EST on The CW.