Kara and Mon-El are met with a surprise when they confront an escaped Leslie Willis, aka Livewire, in a new sneak peek at Monday's episode of "Supergirl."

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"Give it up, Leslie," Supergirl says, rather matter-of-factly. "We've done this before -- the same thing always happens: I win, you lose." However, they've never done it quite this way.

After Livewire (guest star Brit Morgan) seemingly breaks out of prison, Supergirl (Melissa Benoist) is intent on recapturing her. After training Mon-El (Chris Wood), Supergirl takes him with her when she sees Livewire attack the NCPD but things go awry when Mon-El puts Supergirl before the citizens of National City. Meanwhile, James (Mehcad Brooks) decides to come clean with Kara and M’Gann (guest star Sharon Leal), has a psychic attack and collapses into a coma.

Actress Brit Morgan debuted as Leslie in the Season One episode "Livewire," in which the former CatCo shock jock was transformed into the electricity-wielding supervillain following a fatal helicopter accident. She returned to menace Supergirl and The Flash later in the season in the crossover "Worlds Finest." In this week's episode, "We Can Be Heroes," Livewire is apparently free once more, bringing with her "death and destruction."

Airing Mondays at 8 p.m. ET/PT on The CW, “Supergirl” stars Melissa Benoist, Mehcad Brooks, Chyler Leigh, Jeremy Jordan, David Harewood and Chris Wood.