Apocalypse, now? Death by fire, ice, poison gas, suffocation, asteroid. At five moments through history life on Earth was dragged to the very edge of extinction. Now, armed with revolutionary technology, scientists are uncovering clues about what caused these catastrophes. Deep-diving into past worlds of dragonflies the size of seagulls and fishes with guillotines for mouths, they explore how - against all the odds - life survived and what these ominous chapters can tell us about our future.