2051年的地球將面臨一場與外星人的生死戰爭。一群從2051年的時空旅行者唯一的希望是將30年前的人們從過去帶往未來加入抗爭。為了保衛女兒的家園，丹·佛斯特決定同一位科學家和他許久未見的父親前往未來。

高中二年級的春季，女主角高宮菜穗收到一封10年後的自己寄來的信。信上把未來會發生的事情告訴了菜穗，為了讓菜穗不要像自己一樣做出“後悔的事情”，信上指導菜穗應該採取怎樣的行動。

As the end approaches inexorably, the last humans, living millions of years into the future, send a message to the humanity of the present that is both a plea for help and a warning, but also an epic tale of evolution, decline and hope.

After an open mic night, JB and KG get a message from Michael Keaton who tells them that the time-space continuum has been disrupted at the Ford's Theater in 1850 and only Tenacious D can fix it.

Sixteen-year-old Logan is an adolescent uncomfortable in his own skin. Only his science fiction dreams of a better life on Mars draw him away from his ordinary life, which is as equally difficult at home or at school, where he's only seen as an aggressive loser. One evening, he receives a visit from a mysterious man who insists that he has come from the future and that he is also Logan, but forty years older. He then asks the younger Logan to carry out a mission as unexpected as it is important: to save humanity.