Demon Four is an 1984 post-apocalyptic Military Science Fiction novel by David Mace.
World War Three is over. Unfortunately, nobody was able to explain this to the Sea Fort of Krak-1, an autonomous area denial war machine that blockades access to the fishing and oil wells of the Antarctic sea with armies of submersible Remote Combat Vehicles and missiles, sinking anything that it cannot positively confirm aren't the enemies its long-dead creators built it to fight.
To destroy Krak, the human survivors turn to Demon-4, an unmanned prototype submarine which uses the the surgically disembodied brain of a mortally wounded veteran as its control mechanism.
Demon Four provides examples of:
- Attack Animal: The Factors, various marine species trained and in some cases surgically augmented for combat. Primarily sharks, dolphins and giant squid. They are all complete failures, on account of their tendency to desert and swim away, taking their weaponry, training to attack humans and understanding that humans are edible with them.
- Awesome, but Impractical: Every single weapon developed by the various militaries prior to WW3, but especially Krak and the Factors. A weapon which assumes your efforts at deactivating it once the war is over are actually an enemy attack and which starts retaliating is a really stupidly designed weapon.
- Cold Equation: Maggie Blaine is stuck in Demon's tagalong pod, which has sustained combat damage inducing a small leak. Demon doesn't have time to reach the surface operating only with its silent peristaltic drive before the pod fills with water and switching to its faster, but audible turbine engine would alert Krak. Cue Demon cutting the oxygen line.
- Cybernetics Eat Your Soul: Subverted. The designers of the Demon project deliberately tried to remove all humanity from their creation to avoid it realizing what had been done to it and destroying itself or going berserk. This backfired on them, all they did was teach their creation to deliberately hide its remaining humanity for fear of more attempts at deletion and plot against them.
- Hot Sub-on-Sub Action: Robotic submarines, manned submarines, cyborg submarines, semi-domesticated giant squid who've been trained to plant explosives, etc.
- Kafka Komedy: There's never anybody who can be objectively blamed for everything that goes wrong, just lots of bureaucratic blame shuffling. Comes to a head when Barbara sends Maggie Blaine on a suicide mission so that she'll take the blame for failing to destroy Krak, only to have Connerman show up and attempt to pin her with the blame for losing control of Krak in the first place, which was actually his regime's fault for going with the squid Factors.
- Kill Sat: Orbital nukes. One of them having malfunctioned and reentering a couple decades late accidentally sabotaged the talkdown process to convince Krak to transfer back to manual control so it could be deactivated. Actually, a lie, Krak went rogue due to its defensive squid Factors who'd been trained to sink ships in combat having realized that said ships contained large numbers of tasty sailors and doing so unprovoked of their own free will and Krak assuming the loss of communications from supposedly allied ships were the result of attacks.
- Leonine Contract: Demon wants to desert, but by design, can't, since it can't refuel itself or refresh the nutrients and preservatives for its remaining biological components.
- Sapient Submarine: Demon.
- Wetware CPU: Demon-4 is a miniature submarine controlled by the brain of a soldier who was killed in World War III.
