The CW on Wednesday has released the official episode descriptions of "The Flash," "Arrow," "Supergirl" and "Legends of Tomorrow" for the network's mega-crossover.
The superhero crossover kicks off with the Nov. 28th installment of "Supergirl" titled "Medusa." Here's how the network is describing the episode:
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.
Following Supergirl's Thanksgiving-themed outing, the crossover will continue to Barry's world on Central City with the Nov. 29th episode of "The Flash" titled "Invasion!"
When aliens called the Dominators attack Central City, Barry (Grant Gustin) speeds over to Star City to ask the Green Arrow (guest star Stephen Amell) for help in stopping them. Realizing the battle against the Dominators is bigger than they thought, they track down the Legends of Tomorrow, and Barry and Cisco (Carlos Valdes) create a breach to bring back a secret weapon - Supergirl (guest star Melissa Benoist). Once all of the super friends are assembled, they come up with a plan to attack but a shocking secret related to Flashpoint is revealed and suddenly no one is sure who they can trust. Meanwhile, Wally (Keiynan Lonsdale) wants to join the battle against the aliens but Iris (Candice Patton) tells him he's not ready.
On the third part of the crossover, Barry and Kara travel to Star City to help Oliver take out some bad guys. This is how the Nov. 30th episode of "Arrow" also titled "Invasion!" will go down:
Oliver (Stephen Amell) wakes up to a life where he never got on The Queen's Gambit. Robert (guest star Jamey Sheridan) and Moira Queen (guest star Susanna Thompson) are alive and well. Laurel (guest star Katie Cassidy) is his loving fiancée and their wedding is imminent. Everything seems perfect, but Oliver starts to notice small imperfections that make him question this new reality. Meanwhile, Felicity (Emily Bett Rickards) and the recruits take on a new threat with help from The Flash (guest star Grant Gustin) and Supergirl (guest star Melissa Benoist).
Finally, the ultimate showdown of our favorite heroes will take place on the Dec. 1st outing of "Legends of Tomorrow" - which is also titled "Invasion!"
After learning the Dominators' plan for the world, the Legends must work together with The Flash (guest star Grant Gustin), Supergirl (guest star Melissa Benoist) and Green Arrow (guest star Stephen Amell) to kill them once and for all. Meanwhile, Stein (Victor Garber) figures out, with the help of others, how the team can terminate the Dominators, but is distracted by the aberration he realizes he created in 1987.
