When Homer is put in charge of security for Mr. Burns' secret R&D division, he inadvertently unleashes a series of events that threaten Springfield's very existence! If that's not bad enough, an all-too-familiar evil from Springfield's distant future arrives amid the chaos to stake his claim! But wait! Yet another mysterious figure from the future travels back to a current-day Springfield with the town on the brink of destruction! Will this stranger aid the embattled citizens in their darkest hour or make them eat his shorts?