I have recently watched the Classic Doctor Who story The Sea Devils, which sees the Doctor (Jon Pertwee) and his assistant Jo Grant (Katy Manning) visit the Doctor’s nemesis the Master (Roger Delgado) who has been imprisoned indefinitely in a Top security prison, run by Colonel Trenchard from UNIT and is watched constantly by CCTV. The island is also patrolled by armed guards, trained to resist the Master’s hypnotic powers, and even protected by minefields. He claims to have reformed but refuses to reveal the location of his TARDIS. They meet Colonel Trenchard, who tells them that some ships have been mysteriously disappearing. The Doctor and Jo investigate a supposedly abandoned Sea Fort and are attacked, by a sub-aquatic bipedal lizard named a ‘Sea Devil’. They escape to the nearby naval base, HMS Seaspite run by the efficient Captain John Hart; who is in charge of the adaptation of the sea fort for use as a SONAR testing station. The Doctor meanwhile suspects that the Master, has hypnotised Trenchard,into helping him steal electrical equipment from the naval base to build a machine to control the Sea Devils.
The evil Time Lord intends to use the reptiles as an army to enable him to conquer the Earth and he uses the machine to summon the Sea Devils from the sea. Soon, however, a battle for the prison ensues, during which Trenchard, who had believed he was aiding his country against enemy agents, is killed. The Doctor and Jo are forced to flee to HMS Seaspite, where Hart tells them a naval submarine has disappeared. The crew prepare to battle the sea devils. The Doctor investigates in a submarine bell and is seized by the Sea Devils, who take him to their leader.The Doctor enters the Sea Devils’ base and tries to encourage peaceful negotiation, recalling how he had failed to broker an agreement between mankind and the Silurians,
However, before he can negotiate a peaceful settlement, the Sea Devil base is attacked on the orders of the gluttonous and short-sighted politician, Robert Walker, who has arrived at HMS Seaspite to take control of the situation and is intent on repeating UNIT’s actions on Wenley Moor: blowing up the creatures, but this time with nuclear weapons. Hart and Jo are opposed to the attack but at least it allows the Doctor cover to flee, even if he has failed in his initial attempt to sue for peace. The Doctor persuades Walker to allow him a final attempt at negotiation, but in the meantime the Sea Devils capture the naval base, having been aided by the Master, who still wishes to instigate a war. The Master then forces the Doctor to help build a machine to revive Sea Devil colonies all over the world. Returning to the Sea Devil base the Master activates the device….