The prehistoric Earth is dying. Thunderclouds move across the skies, cloaking the land in darkness. The seas crash and boil as the rain turns to acid. The remnants from the Silurian race place themselves in suspended animation, deep below the surface. One day they’ll awaken and reclaim their world… The TARDIS provides landed around the Galapagos Islands, a desolate outcrop of rocks shrouded in mist and fear. In the arrangement of Baquerizo Moreno, a couple of rumours that prisoners have been mysteriously disappearing from the gaolhouse. A fisherman has been driven crazy by something he saw in the caves. And the Doctor and Evelyn are not the only fresh arrivals; there is also a young natural philosopher by the name of Charles Darwin…