This four show crossover extravaganza will take place over a series of four episodes throughout the week, one for each of the shows. The first two-minute trailer shows the arrival of the "Dominators", a not-very-friendly alien armada that the superheroes will have to face together for the good of humanity.
Barry Allen (Grant Gustin), also known as Flash, seeks the help of Oliver Queen, the Green Arrow (Stephen Amell), to stop the impending invasion of Star City. When they realize that the battle is bigger than they thought they will have to locate the Legends of Tomorrow team and create a breach that will bring back their secret weapon: Supergirl (Melissa Benoist).
The countdown begins
The series-event begins at the end of an episode of 'Supergirl' and continues in the other series. It is based on a strip of comics of 1988 titled also "Invasion!" Which narrates how various alien races under the command of the "Dominators" will descend to Earth to end the threat posed to them by the metahuman community on our planet, before it continues to grow. Of course the aliens have their own plans for superheroes and pretend to create a super-race of Dominators that can subdue the rest of the species.
In the television version, instead of assembling a dangerous alliance, the Dominators apparently control the minds of the aliens who join them. This new twist led EW to hint that even heroes might be forced to fight each other at some point, if dominators can control them.
The Invasion commences on the 28th of November.