Siberian permafrost keeps giving up mammoth remains intact enough to yield usable DNA, and this film follows the geneticists trying to splice cold-resistance genes from that DNA into Asian elephants, the mammoth's closest living relative, with the hope of releasing hybrid animals onto the tundra. In Australia, researchers extract genetic material from preserved thylacine embryos held in museum collections and attempt to replicate it in a related marsupial mouse. In Berlin, biologists inseminate eggs harvested from the world's last two northern white rhino females with sperm frozen decades ago from now-dead males, racing to save a species that functionally no longer has a breeding male. Interviews with the scientists running these labs sit alongside skeptical biologists who argue that de-extinction projects misallocate money and attention away from habitat loss and the causes of extinction in the first place. The film does not settle the argument, laying out the lab work in detail while leaving open whether reviving a species means anything if the world that killed it is still there.