Death is life's greatest certainty. But that may be about to change. Scientists have discovered an immortal animal that may hold the secret of endless regeneration. They're on the brink of editing our DNA so that we can cure ageing like a disease. Or is dying necessary for the survival of our species?

To maximize longevity, you might think it’s best to play it safe and stay cozy. But some scientists believe we should do the opposite, as exposure to extreme temperatures can trigger our bodies’ own defenses against the killer diseases of old age. Chris heads for the freezing Arctic with his brothers Liam and Luke to take on the ultimate cold therapy.

Chris turns to longevity doctor Peter Attia to find out how changing his eating habits can help his quest for longevity. Ironically, the answer is to eat no food at all for four long days. If he can bear the hunger, fasting will unlock his body’s own anti-aging powers and give Chris the edge he needs when he tries to hunt for his next meal … by spearfishing off the Great Barrier Reef.

Over the past year, Chris Hemsworth have been exploring the science of living longer, doing everything he can to hold back time. But whatever he does, sooner or later, aging and death will win. Now Chris is facing his most extreme and emotional challenge: three days in a retirement village while wearing an aging suit that turns the simplest activity into a Herculean task. He'll be carrying an extra 30 pounds around and shoes that will make him unbalanced, apart from glasses to see improperly and acoustic earmuffs. Later on, Chris is going to do a death-bed meditation. He’s testing the theory that the best way to combat aging and fear of mortality might not be to fight it but accept it,