One of the things that fans look forward to with The CW’s superhero universe is the annual crossovers between the shows, which only gets bigger each year as the network adds more heroes to the Arrowverse.

With this year being a true four-part crossover between The Flash, Supergirl, Legends of Tomorrow and Arrow, The CW has announced the title as ‘Crisis on Earth-X’.

Below is the official synopsis for the crossover:

With all of the heroes in town to celebrate Barry and Iris’s wedding, villains from Earth-X crash the festivities with a deadly agenda.

“We conceived this year’s crossover to be evocative of the annual Justice League/Justice Society crossovers we grew up with and looked forward to as kids,” said executive producers Marc Guggenheim and Andrew Kreisberg.

The crossover begins on Monday, November 27th with Supergirl followed immediately by Arrow. It will then continue on Tuesday, November 28th with The Flash and Legends of Tomorrow.