Set 15 years after the last Power Rangers series, POWER RANGERS S.P.D. ('Space Patrol Delta') features an all new cast of characters. The evil alien Emperor Grumm, along with his army of cybernetic soldiers, heads for Earth with conquest on his mind. Only the Power Rangers, an elite group of cosmic warriors, can stop him. The problem is, there are only a few Rangers who are ready for the task, while the others are still in the stages of training at the Ranger Academy. With Grumm's machinations already in effect, the established Power Rangers will have their hands more than full, while the rookies will themselves be severely tested by the alien's plot.