When Lloyd Garmadon Jr. frees the Skulkin Army and his father, Lloyd Garmadon Sr. from the Underworld to take over Ninjago, Lloyd's twin brother, Wu Garmadon, recruits Kai Smith, who is trying to find out what happened to his parents, to join his team of Power Rangers, as the new leader.

In the year 2990, the universe finds itself at war again. But aiding in preserving the peace are the Power Rangers, brought back after centuries of inactivity to fight on behalf on the universal monarchy. But the Rangers will soon learn that evil lurks around every corner.