The fifth season takes place in 2036, 24 years after the conclusion of the fourth season; in 2015. Numerous Observers from the 27th century, having made the Earth uninhabitable in their own time, traveled through time to take over the Earth from humanity, instituting a Purge to kill off a large fraction. The remaining humans are tamed in an Orwellian manner by the Observers and their human Loyalist collaborating soldiers, though an underground resistance still eludes capture by the Observers. A common scene used through this season is one where Peter, Olivia, and their young daughter Etta enjoying a picnic on the day of the Observers' arrival and conquering of the Earth in 2015; Etta goes missing in this scene during all the confusion and destruction. Walter had been warned of this by September before the Observers' appearance and, with his help, devised a plan to defeat the Observers in the future, scattering key elements across various locations and leaving messages for the future on video tapes in his lab, which he then encased in amber to protect their discovery.
