M022 - Bloodtide

When the Doctor and his companions visit famous figures in history, the peril they find themselves in tends to connect back to the celebrity guest. Eccelston and Charles Dickens dealt with ghosts, Tenant and Shakespeare dealt with witches, so it is appropriate that Colin Baker and Charles Darwin face the Silurians.

While visiting the Galapagos to let Evelyn see Charles Darwin form his theory of natural selection, the Doctor hears about demons in the caves. It turns out that some Silurians have awoken from their cryosleep and they are not happy to find their planet infested with monkeys.

Sometimes the script indulges Darwin's thought process a bit too much, allowing him to verbalize his entire theory as Evelyn pops in to say, "Go on," and "That sounds reasonable," but the concept is still strong. And when evolution becomes an important plot point, Darwin makes for an appropriate supporting part in a fairly thrilling adventure.