Janitors can become maddened for a variety of reasons. It is important to learn to recognise the telltale signs, among which are an empurpled face, wild dishevelled hair, and grunting. If you find yourself in a locked building with a maddened janitor, the best thing to do is to confine him in a cupboard while you desperately seek a key to the locked door, thus allowing you to flee.

There are several accounts of people upending the janitor’s bucket and cramming it over his head. The idea seems to be that, robbed of sight, with an upturned bucket on his head, the maddened janitor will be rendered harmless. This is absolutely wrong. In these circumstances, the janitor merely becomes more maddened, and brandishes his mop the more menacingly, plodding sightless along the corridors of the locked building like unto a zombie. If he manages to corner you, and whack you on the bonce with his mop, you will fall unconscious, and when you awake you too will have become a maddened janitor, destined to roam the corridors and cubbies of the locked building forever more.

In any town or city you are likely to see buildings shuttered and abandoned, boarded up or slated for demolition. These are the haunts of whole colonies of maddened janitors, roaming eternally in the darkness. Sometimes one of them might stumble upon a bunch of keys, and rattle them, and seek to find a door they will unlock. To date, no maddened janitors have ever managed to escape into the open streets. It is thought they would perish at the instant of leaving their building, but nobody is quite sure. That is why boardings-up are made as fast as possible, not just with hardboard but with planks of wood and chains and electric alarm systems and, in some cases, patrolling dogs.

It can happen that one of the smaller and stupider patrol dogs will find its way into the building through a duct or flap. It is unlikely ever to emerge, for it will be set upon by the maddened janitors with their mops, and no matter how shrill its yapping, it is doomed. To what purpose the maddened janitors put the battered corpses of small and stupid patrol dogs is a matter of conjecture, one which we may not wish to dwell on if we are ever to get a good night’s sleep.

Several bright minds have pondered the possibility of somehow unmaddening a maddened janitor. Can they be proffered gifts, perhaps, to placate them? One brave researcher worked his way through a hamper full of possible offerings, including buns, biscuits, ice cubes, pre-stunned puppies, new mop handles, linctus, and feathers. The results varied. Maddened janitors by turns quaked, groaned, had convulsive fits, or thumped their heads repeatedly against walls. But not one was unmaddened.

It might be thought demolition of the building housing a maddened janitor colony would finish them off. But no. Often, from the rubble, in the night, groans can be heard, and the clank of mop handle against bucket, and the faint rattling of a bunch of keys. They are down there somewhere, furious now, madder than ever, waiting only to rise up. But as they cannot bear the open air, they wait, and wait, until such time as a new building rises in place of the old. Its gleaming new corridors and space age swishy automatic doors and CCTV cameras promise a new dispensation. Tenants are not hard to find, sprightly young dotcom startups for example.

One night, a few months after the company has moved in, an eager young whippersnapper is working late at his desk, sweeping his fingertips back and forth across the screen of his iFaff, generating a revenue stream. He is tiring, and in need of coffee, so heads off along the corridor to the hot drink dispenser. The only sound is the low hum of nocturnal light and power. As he approaches the machine he rummages in his pocket for coinage. The clinking of metal is enough to rouse, from the subterranean depths of the building, a maddened janitor. He is one who had a bucket upturned over his head. He brandishes his mop, and clambers from the pit, into the boiler room, and along the basement corridors, through the fuse cupboard, to the stairs. And up he comes, sightless because of his bucket, implacable, grunting, feeling his way forward with his outstretched mop. Were you there, a fly on the wall, you might just be able to see bits of small and stupid dog entangled in the strands of the mop.

The keen young web entrepreneur has made his selection from the numberless coffee choices available, and is listening to it hiss and glug into a paper cup. It is the last thing he will ever hear, because he is an inattentive young man who knows nothing of the hidden world.

But you do, now. And you will not be inattentive, as you trudge in the autumn rain along the boarded-up high streets of your dismal town. You will hurry your pace, your collar pulled up, puffing on a gasper, listening for the yap of patrol dogs, muttering a prayer.