The TARDIS materalises at a secret naval base off the coast of Northumberland during the Second World War. Dr Judson, a scientist there, has created the Ultima Machine, an early computer designed to break German codes. But Judson also has a much more sinister use for the machine. He plans to translate the ancient runes in a crypt of the nearby St Jude’s Church, which will release Fenric, an evil entity from the dawn of time whom the Doctor trapped seventeen centuries earlier.

As Fenric’s Haemovores attack, the Doctor must once again face the entity in a battle which will reveal devastating truths for Ace…