It is a truth, universally acknowledged, that the moment you utter the immortal words, “Oh, it’s nothing to worry about,” that particular nothing immediately becomes a something. The city of Ankl-Morswine was no stranger to somethings to worry about, especially somethings replete with far too many legs and an alarming overbite containing too many teeth.

So it was, when Sergeant Fred Colon of the City Watch noted, “’s’probly a spider, in’t it?” and prodded the writhing, shimmering thing with his trusty truncheon. The thing, clearly unimpressed by truncheon prodding, scuttled sideways and into the dingy shadows of an alley, leaving behind a small pile of what may, or may not have been skin.

“That,” said Nobby Nobbs, flicking the skin off his boot with his slightly more battered truncheon, “ain’t no spider, Sarge.”

Which is how, some hour and a quarter later, Bertram Sproggins, proprietor of Sproggins & Sons Pest Control (“Catch It, Kill It. We Also Sell Pies”), found himself face-to-face with unbridled weirdness.

“Let’s get this straight,” said Sproggins Senior, adjusting his night vision goggles and squinting at the Watch officers. “It’s got… how many legs?”

“More than eight,” said Nobby, helpfully. “But fewer than… loads.”

Fred Colon scratched his head. “It were glowing, too. Sort of… pulsating. Not bloody right if you ask me.”

Bertram sighed. Ankl-Morswine had a ‘history’ with glowing things. The river Ankl, as it limped turgidly through the town, glowed on wet days, and some of the pies in the Shades glowed on purpose.

“Alright,” he muttered, hoisting his equipment bag. “Let’s have at it then.”

The thing, when eventually cornered in a damp cellar shimmered faintly in the gloom, a shifting mess of chitin, fur, and what might have been feathers, though only if you’d never seen feathers before. It moved like watery custard on the back of a spoon, and as Sproggins Snr. crept closer, he could hear it humming.

“Well, that’s not right and its not natural,” he muttered, which was actually not an unusual utterance in Ankl-Morswine.

He pulled out a sturdy brass contraption and gave the thing a squirt of his strongest pesticide concoction. There was a strong whiff of burning, old and overworn socks.

The thing abruptly stopped humming. It turned, and for a moment, Sproggins thought it looked hurt. Not just irritated or angry, but genuinely emotionally wounded, as if it had just been chucked by its girlfriend.

Then it exploded.

Back at the Watch House, Sproggins nursed a cup of tea and tried not to think about what he’d just witnessed.

“Well?” asked Fred, “you reckon it’s gone for good?”

Sproggins stared at him, then at the teacup, which was glowing faintly in a way he decided not to acknowledge.

“I’ve no bloody clue what that thing was,” he said, “but if it comes back, you’ll not need me, you’ll need a bloody wizard.”

“Well, we’ve got plenty of those around here. Sadly.”

And somewhere, in a dark cellar of the Unseen University, a many legged thing hummed softly to itself.