New Supergirl Synopsis Previews Start of CW Superhero Crossover

In 2014, "The Flash" and "Arrow" crossed over for the first time; they did it again last year in a two-parter that helped introduce "DC's Legends of Tomorrow." This year, The CW looks to up the crossover ante this month as "Supergirl" joins the fray in a four-show event running through each of the network's DC Comics-based shows, from Nov. 28 to Dec. 1.

Things will start on Nov. 28 on "Supergirl," before continuing on consecutive days with "The Flash," "Arrow" and "Legends of Tomorrow." While it's already been established by the shows' producers that the "Supergirl" installment is not fully a part of the larger crossover story, it is where it starts out -- and a new synopsis from the episode, "Medusa," freshly released by the network, spells out just how Kara gets involved, despite living in a separate corner of the multiverse from the other three shows. The synopsis also gives insight into the episode's main plots, involving many of the show's ongoing storylines.

As you might expect, Barry Allen/The Flash (Grant Gustin) and Cisco (Carlos Valdes) are key to bringing Supergirl into the action -- following the Flash's guest appearance last season on "Supergirl," when the show was still on CBS. Here's the full synopsis for "Medusa," which airs 8 p.m. Monday, Nov. 28 on The CW:

A NIGHT OF CONFESSIONS; THE EPIC SUPERHERO CROSSOVER KICKS OFF TONIGHT — Eliza (guest star Helen Slater) comes to town to celebrate Thanksgiving with her daughters. Alex (Chyler Leigh) decides it’s time to come out to her mother; Kara (Melisa Benoist) is shocked when Eliza suggests Mon-El (Chris Wood) has feelings for her, and Winn (Jeremy Jordan) and James (Mehcad Brooks) consider telling Kara the truth about the Guardian. Meanwhile, CADMUS unleashes a virus that instantly kills any alien in the vicinity so Kara enlists an unexpected ally – Lena Luthor (Katie McGrath). The epic superhero crossover kicks off tonight when Barry Allen (guest star Grant Gustin) and Cisco Ramon (guest star Carlos Valdes) seek Kara’s help with an alien invasion on their Earth. Stefan Pleszczynski directed the episode written by Jessica Queller & Derek Simon (#208). Original airdate 11/28/2016.

Starring Melissa Benoist in the title role, "Supergirl" airs Mondays at 8 pm ET/PT on The CW. The series also stars David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott and features appearances by Calista Flockhart's Cat Grant.

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