Washington D.C. [USA], Nov. 24 : Looks like fans of ' DC Comics' are in for an incredible treat with the CW's giant four-show crossover that begins on Monday.

Judging by the new trailer, the superheroes and vigilantes band together to fight against some seriously scary aliens, called the Dominators, that have come to Earth and are ready to basically exterminate humans.

The four-show crossover combines Supergirl, The Flash, Arrow, and ' Legends of Tomorrow' and will take place over four nights next week, staring Monday through Thursday, on brand new episodes of each show.

Apart from the incredible special effects and one-liners from favourite quippy heroes, there are a few moments that might worry the watcher.

That little speech Barry Allen ( The Flash) is giving about how it has "been an honor" to work with everyone sounds an awful lot like the kind of speech one would give when all hope is lost.

The ' Heroes v Aliens' event starts with 'Supergirl' on ' CW' broadcast network. (ANI)