After the population is restored following Thanos' click, an unexpected tragedy forces a group of ancient aliens who have been living on Earth in secret for thousands of years out of the shadows to reunite against mankind's most ancient enemy, the Deviants.

Bea, Thomas, and the rabbits have created a makeshift family, but despite his best efforts, Peter can't seem to shake his mischievous reputation. Adventuring out of the garden, Peter finds himself in a world where his mischief is appreciated, but when his family risks everything to come looking for him, Peter must figure out what kind of bunny he wants to be.