Un dia el món es paralitza quan un grup de viatgers en el temps es transporta des de l'any 2051 per lliurar un missatge urgent: La humanitat està perdent la guerra mundial contra una espècie alienígena letal. L'única esperança de supervivència és que els soldats i els ciutadans del present siguin transportats al futur i s'uneixin a la lluita. Entre els reclutats hi ha el professor d'institut i pare de família Dan Forester (Chris Pratt) qui, decidit a salvar el món per la seva filla, s'uneix a una científica brillant (Yvonne Strahovski) i al seu pare (J.K. Simmons) en una recerca desesperada per reescriure el destí del planeta.

A girl mysteriously receives advice from her future self and as a result her group of friends, along with a newly arrived, troubled classmate, learn how to be better friends and a better community.

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.