'Supergirl' Introduces a New Worldkiller in "Both Sides Now"

The CW has released the official synopsis for "Both Sides Now," the February 5 episode of Supergirl.

In the episode, the DEO manages to capture another Worldkiller, and hope that doing so will provide them with much-needed guidance in their battle against Reign. However, the Worldkiller gets loose and things look like they are going to get much worse before they get better.

"What I think is really special about this storyline is it's a slow play and you'll get to see this whole heartbreaking story unfold in a really -- they're taking their time with it, and we have the time to do it," Odette Annable, who plays Reign, said back in October. "I think the audience is going to hopefully relate."

Until the end of this week's episode, Reign did not even know there were other Worldkillers. That revelation is a potential game-changer, and makes her an even more formidable threat, as the potential for an army of beings on Reign's power level looms over the second half of the season.

Introduced in 2012, Reign's history is a mystery even to her. She knows her name, that she's a Worldkiller and not much else. As for Worldkillers themselves, in comics they're bloodthirsty, uncontrollable, super-powerful biological weapons created on Krypton who are, as the name Worldkiller implies, a threat to all living beings. Five of these Worldkillers survived the destruction of Krypton, including Reign and as we saw at the end of last season, she was sent to Earth in a pod, much like Supergirl herself.

Also in the episode: the Legion of Super-Heroes' ship is apparently damaged, leaving them stranded in the present day.

A veritable "Legion Lost," if you will.

You can check out the official synopsis below.

The DEO captures a second Worldkiller, Purity (guest star Krys Marshall). Supergirl (Melissa Benoist) and Alex (Chyler Leigh) use very different methods of interrogation with Purity in the hopes of finding out how to defeat Reign (Odette Annable). However, Purity escapes and attacks the city's subway tunnels.

Meanwhile, J'onn (David Harewood), Winn (Jeremy Jordan) and Mon-El (Christopher Wood) band together to fix the Legion ship.

Jesse Warn directed the episode written by Jessica Queller & Paula Yoo.

Supergirl airs on Monday nights at 8 p.m. ET/PT on The CW. "Both Sides Now" will debut on February 5.