The Flash followed up to the end of Supergirl when Barry and Cisco went to Kara for help on their Earth. Barry is stunned to discover aliens are coming to their Earth and it has happened before. They have taken people to conduct unknown experiments on them to find information. In order to stop them, Barry recruits all of his superhero friends to aid in stopping the aliens.
In the meantime, Wally is desperate to use his powers, but everyone else does not think he is ready. He wants to be trained so he tries to get H.R. to train him.
Barry works with the superheroes but then a revelation about Flashpoint leads to difficulty in trusting people. Oliver and Barry are left out only for the rest of the superheroes to be in trouble.
While the battle is not over and continued on Arrow, we got an exciting start to the battle for Earth. The battle will continue Dec. 1 on Legends of Tomorrow. For a refresher, let’s go back to the beginning on Flash with “Invasion!”