When the Warstar Alien Armada plans to destroy Earth, an entity, by the name of Gosei, recruits a group of teenagers to become the Power Rangers Megaforce and eventually evolve into Super Megaforce. However, they need more power than they think to stop this armada. To achieve this, Gosei grants them the ability to use the powers of legendary Power Rangers, rangers from the past, and later unite with the actual Legendary Rangers for a huge, epic battle the Rangers have never encountered before.