This is the premise of James Herbert's 1974 Nightmare Fuel novel, which began with the oft-repeated observation that in London nobody is ever more than twenty feet away from a rat. Herbert wondered what might happen if in a city of eight million people, twenty million or so rats were to develop a dim awareness that they not only outnumbered people but could find unity in strength. His rats mutate, become larger, fiercer, more intelligent, and can transmit a deadly necrotic plague into the bargain. And London is suddenly in trouble.
Criticized for its graphically explicit nature, both in terms of sex and violence,note and seen by others as a political satire on the fact that thirty years after the end of World War II, Britain's capital city STILL had slums and uninhabitable bomb-sites which were breeding rats and disease, the book sold out within three weeks and went direct to its first of many reprints.
The novel received a film adaptation in 1982 as Deadly Eyes. There have been at least two sequels, including Lair and Domain and the graphic novel The City.
This horror story spawned an uncontrollable swarming horde of tropes, including:-
- Badass Teacher: Harris from the first book. He survives many attacks from the rats whereas nearly everyone else gets killed immediately, and only suffers serious injuries in the climatic battle.
- Brain Food: The mutant rats have a particular fondness for this particular part of their victims.
- Breather Episode: Chapter 8 is Harris and his girlfriends's weekend break in the country.
- Bury Your Gays: The first victim of the rats is an alcoholic vagrant whose downfall began when he had an affair with a much younger man, which was enough to ruin him in the climate of the seventies. This trope is averted, though, as his story is presented as a tragedy.
- Crapsack World: London is this to several of the introduced characters, especially the mis-used Irish tramp who as a girl came to the city with bright hopes, but who degenerates into sexual abuse and alcoholism. Becoming one of the first victims of the rats is almost a blessed relief. It gets infinitely worse in Domain after the nuclear attack.
- The End of the World as We Know It: As book three opens, London is comprehensively trashed in the nuclear attack and several million people are killed.
- Eye Scream: As the rats prefer eating peoples' brains (see above), their favorite mode of attack is to chew their way to the "tasty candy center" of a victim's skull through the eyes.
- Humans Are Flawed: There is no hero who saves the day. Practically all the human characters are depicted as fairly flawed, seedy, unattractive, even repulsive, people who are wholly ineffectual against the peril.
- I Love Nuclear Power: The original mutant rats came about as a result of nuclear testing on the islands around New Guinea.
- Kill 'Em All: Practically all the introduced human characters get killed, often horribly.
- Rat King: The alpha of the killer rats stalking London is a white, hairless and obese rat with two heads.
- Redemption Equals Death: Foskins in the first book. After being disgraced and fired for his failure to end the threat of the rats, he attempts to redeem himself by locating the rats' lair. He does so, but when he does find it, he's set upon and killed by the mother rat's guards, although he takes two with him, and it's through following him that Harris finds the nest and kills the mother rat, ending the threat for the time being.
- Rodents of Unusual Size: The mutant rats are three or four times normal size.
- Swarm of Rats: The rats hunt in supersized packs so as to be sure of bringing down a human.
- What Measure Is a Non-Cute?: the book would not have had the same impact had the animal stars been rabbits, hamsters or kittens.