STEVE Ely lives in the countryside of West Yorkshire. His back garden is large enough to have had an infestation of rats over a period of two years.

It was while dealing with this problem that the idea of a novel began to take shape in this former teacher’s head (he used to teach the children of the Barnsley writer and broadcaster Ian McMillan). The result, Ratmen, is one of the most engrossing and appalling reads I have had for a long time.

There are two main characters, The Man and his apprentice, The Boy. The Man is a professional exterminator of rats. The Boy, a refugee from a dysfunctional family of slobs and petty criminals, is in no man’s land looking for a path to follow. The Man teaches The Boy how to kill rats – with sticks, gas, dogs, poison and petrol.

There is no compromise. As The Man frequently tells his doubting apprentice, rats are the enemy of the humans race. They are the carriers of disease, the bringers of plague and Ebola. They are the vile embodiment of a conspiracy to annihilate the humans race – aided and abetted by animal rights activists, pet shop owners, laboratory scientists and cult religious worshippers of the rat ion South Asiathe Indian Sub-Continent.

This is how The Man talks to The Boy – neither of them are given a name or much a back-history: “The orange-fanged, scaly-tailed, oily-furred, nail-clawed nemesis of man, the bone-biter, throat-leaper, nerve-ripping screamer, death, war, famine and disease. That’s what was lurking in the shadows of that shed. Not just some ‘cute furry creature’, but the end of the world itself.

“The rat is the mirror of man, the Mr Hyde to his Dr Jekyll, the demon to his angel, death to his life. Man creates sewers to carry away his filth; the rat mocks him and thrives on his ordure, transmitting man-scat to toxic malevolence, returning it to man as pestilence and plague.

“Rats come creeping through these cathedrals of filth and swarm to the human surface through cracks and hell-holes, bringing their warfare like genocidal missionaries, bearing death in the bite and the blood, in their toxic chrism of urine and faeces. For a rat, the sewer is temple, barracks, maternity ward. The Pentagon, Wewelsburg, Tora Bora, Mount Zion, the holy of holies.

“If the human race became extinct overnight, rats wouldn’t die out – not a chance. On the contrary, their population would explode – humans are the main thing keeping their numbers down. They’d thrive on the rotting remains of our civilisation before moving on to the animal and vegetable worlds. Left to it, rats will consume the Earth. Only we stand against them.”

If this strikes you as the highly-charged, almost poetic, language of fanaticism you’d be right. Ely admits that when writing the book he came close to identifying with The Man, principally with his unremitting hatred of rats, not his world view of humanity.

This is what happens to people who identify with a cause so completely their certainty admits no ambiguity, no doubt. The gap between exterminating rats and exterminating people is but a step for such people.

In light of what’s going on in parts of Syria, Iraq, Afghanistan and the Congo, this stark, tightly-written book makes perfect sense.