Around 540 million years ago, the ancestors of almost all complex organisms that exist today suddenly emerge in the shelf seas of the Cambrian. But plate tectonics and climatic fluctuations keep throwing the new life off track. Nevertheless, evolution progresses and even manages to make the leap onto land. But around 250 million years ago, life has to pass its biggest test, yet: massive volcanic eruptions trigger the most severe of all mass extinctions in Earth's history.