Supergirl: Medusa Kicks Off Invasion In New Featurette

Fans of the DC TV series which air almost every night of the week on the CW are buzzing this week as it marks the beginning of what promises to be an epic four-night crossover event with Supergirl, The Flash, Arrow, and Legends of Tomorrow.

It all kicks off tonight with Supergirl, CW's Monday night DC Comics show. In promotion of the new episode, the CW has released a new featurette for the new episode of Supergirl. The video offers a look inside things to come, specifically involving the journey we went on to the Fortress of Solitude.

"This week we learn why they needed to gain access to the Fortress of Solitude -- because inside is the recipe for the Mesuda Virus," said Ali Adler, Supergirl executive producer.

The featurette also shows Barry's arrival in Kara's National City as he recruits her to take on the aliens which will be invading his Earth.

"We'll see The Flash appear alongside Cisco," Adler said. "What we know from the Flash is that they meet to fight the Dominators."

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.

NEXT: The Flash, Arrow, Supergirl, Legends of Tomorrow Crossover Trailer / First Look At The Dominators / Invasion! Crossover Promo Photos / Potential The Flash Spoiler Spotted On Set / Will Joe West Die During The Invasion! Crossover?

Supergirl airs Mondays at 8 p.m. ET/PT; The Flash on Tuesdays at the same time; Arrow on Wednesdays and DC's Legends of Tomorrow on Thursdays. All four series air on The CW. The "Invasion!" crossover will air beginning November 28.