When Captain Mills (Adam Driver) discovers that Koa (Ariana Greenblatt) is the only other survivor after their ship crash lands on a remote planet, they have a communication barrier because of the language Koa speaks in 65. Mills had left an ill daughter a little older than Koa in order to pilot the ship on a multi-year mission that would pay for her treatment, but crash-landing on what turns out to be Earth 65 million years ago changes his plans. He must help guide Koa through unfamiliar terrain while 65's dinosaurs and prehistoric animals, and parasites hunt them.