Somewhere in the depths of the Yorkshire countryside, two middle-aged police officers sat peacefully at the roadside, beside a five-bar gate. Their police car was parked, and unoccupied. The elder man, a silver-haired copper, was busy with a portable barbeque, trying to cook four sliced bananas in tinfoil. His companion, a burly, black sunny-faced officer who looked as if he'd rather hug you than arrest you, was resting his back against the dry-stone wall. He had picked a daisy, and was peacefully pulling off its petals with his big fingers. If he was wondering if someone loved him, he said nothing.

PC Cooper looked up from prodding the bananas with a spatula.

"That's a life there, yer know."

PC Walsh looked up from the daisy.

"You what?"

"That poor little flower you're pickin' at."

"It's not a flower. It's a weed. It's police work. This weed could be a controlled substance."

"It's a cute li'l flower, and you're pickin' it to bits. If that was a person, it'd be accusing you of police brutality b'now."

Walsh grinned. He pulled off the last petal, and threw the remains of the defenceless daisy over his shoulder.

"How you gettin' on?"

"I'm sure this is 'ow you do it. I saw our Ken cook these. 'Ere, stand by with the brown sugar."

Walsh went round and opened the boot of the police car. He took out the green first-aid kit and opened it. It contained, not bandages or disinfectant, but a small spice rack and a selection of sugars and syrups. Police work gave you a sweet tooth.

As he was taking the goodies back to his friend, a balding, moustached old man with white hair came unicycling along the lane. The coppers barely paid him any heed. They knew, by now, that this countryside was filled with eccentric old men, and it was quite usual to see one of them on a one-wheel cycle, especially on a Monday morning.

As he came nearer, he gave them a grin.

"Morning."

Walsh decided to play along.

"Is this your vehicle, sir?"

"Do I look like the sort of man who'd ride another's unicycle?" Alvin kept moving, somehow keeping his balance. "If you're thinking of giving it a ticket, there's nowhere to put it."

They were interrupted by a muttered curse from Cooper, and a column of smoke rising from burning foil. Walsh shook his capped head in despair.

Alvin hovered beside them. He hid a smile.

"Have you seen any sign of that escaped convict, then?"

Both coppers looked uneasy.

"Escaped what?" Walsh spoke his mind, but Cooper was quicker off the mark.

"Oh, the escaped convict. Yes, sir. Top of the agenda. Just remind me?"

Alvin smiled.

"The invisible one. Escaped last night. From a maximum-security prison. You've seen Die Another Day? The invisible car? This man's found a way to make himself unseen to the human eye. And policemen, too."

Cooper seemed about to scoff at this strange story, but Walsh looked more thoughtful. Alvin still sounded cheerful.

"Make him difficult to catch, I would have thought. Anyway, keep an eye out for him. Or an ear. Evenin' all."

He cycled on, disappearing into the distance. Walsh gave his mate a glance.

"I suppose that was all jollop?"

"'Course!" Cooper forced a laugh. "Convicts, turnin' themselves invisible... did you read anything in the bulletin, this mornin'?"

"Didn't read the bulletin." Walsh gazed after the vanishing Alvin. Cooper could tell his friend really wanted a go on the unicycle.

"C'mon. Let's see if these... what're you lookin' at?"

Walsh was staring at the road. Slowly, he pointed.

A row of white footsteps led towards the gate.

Walsh looked across the field. The grass was fairly long, and footsteps wouldn't carry any further, but someone had definitely been this way.

"Someone's definitely been this way," said Walsh. "You don't think..." He moved back towards the police car. "Mebbe we'd better radio for assistance."

"What, for footsteps?" Cooper shook his head. "A right muffin I'm gonna look, callin' for armed response against a row of footsteps."

"I s'pose it's our duty to go an' look."

Cooper cast a last, sorry glance at the barbeque.

"I s'pose it is."

"But... least sign of danger. We radio for backup?"

"Yerron. C'mon."

After they had found their truncheons in the boot of the car... beneath the deckchairs and the patio umbrella... they opened the gate and started to make their way across the field.

"At least he shut the gate, this convict," said Cooper. "He may be a menace to society... but at least he knows the Country Code."

"What if he's armed? How will we know?" Walsh took a cautious look across the pleasant English scene. "How are we gonna get the cuffs on him? D'you think they'll stay visible?"

"You realise he could be right in front of us, now?" Cooper blinked. "Or be'ind us?"

Together, they reached out their hands in front of them, searching for the invisible man. Walsh flinched as his fingers met something... before he realised it was his colleague's shoulder.

As usual, Cooper was trying to play the experienced man.

"What would you do, if you were on the run?"

"I'd go to me mam's."

"No... 'im."

Walsh shook his head. "He wouldn't go to me mam's. 'Least, I 'ope not."

"You'd look for cover, wouldn't yer?" Cooper pointed to distant trees. "'E could be out there, in them woods..."

The two coppers exchanged glances. Slowly, clutching their truncheons firmly, they made their way towards the forest.

Once they had left the field, Walsh pointed again.

The white footsteps were back, leading across the muddy ground and into the trees.

Cooper decided to take charge. He took a very small step towards the forest.

"A'right. We've got these woods surrounded. Come out, with your hands where we can't see them."

There was silence.

"If you don't show yerself, it'll only make it worse for yer."

Another silence.

Then suddenly, they saw leaves and branches start to move. It looked for all the world as if someone were dodging among the trees, running for cover.

Cooper and Walsh exchanged glances again, and gave chase.

A short distance away, in the woods they had all known since boyhood, Hobbo, Entwistle and Alvin heard the sound of two oversized coppers crashing about in the undergrowth. Alvin chuckled. He was still on the unicycle, keeping his feet off the ground.

On the soles of both his shoes was tacky white paint.

"Bit of luck, my treading in that paint. I reckon it's been in that shed since old Compo's time."

Nearby, Entwistle was tending a large and ancient wind machine. It was powerful, and had nearly had Alvin's cap off, twice.

"Been waiting for a chance to use this. They left it with me for repair when they came to make that film. Forgot to pick it up again."

Hobbo was trying to look stern and wise.

"It's not just a prank, of course. It's an important test of our police service. Public duty. It certainly beats Home Office inquiries."

"What if they find us?" Entwistle asked.

"Then we remember my secret agent training, from Primrose Dairies. Take cover behind the trees." Hobbo smiled. "But somehow, I don't think they're coming this way."

Cooper and Walsh had been crashing about amongst the trees for what felt like hours. They were no longer in control of the situation... if they ever had been. For all they knew... which was little... they were trapped in a dense forest with an escaped criminal they couldn't see. Every branch upon their shoulders, the slightest noise made them jump and spin around in fear. Cooper was longing to be back at the station... or even at home with the wife... while Walsh was beginning to wish he'd stayed in Liverpool, and taken a job at his cousin Mick's cafe.

"'Ave you ever thought about early retirement?"

"There's times when I'd really love to be a librarian. I could ask Miss Davenport..."

"What 'appens when we don't report in?"

"I s'pose this is my punishment for hurting that daisy. Cute li'l plant-form, an' a big fella like me comes and picks it to bits."

"An' I left those bananas on!"

"We've got no food. S'pose we have to eat each other? Who goes first?"

"You're the elder."

"You've got more meat on you..."

Suddenly, there was light ahead of them. As one man, Cooper and Walsh surged forward...

...and out into the lane.

Both of them stared at the sight of their own police car, directly opposite them.

"We've been goin' round in circles!" Cooper made a last dash for the car, and stood there, panting.

"An' look!" Walsh went to the barbeque, checked the tinfoil packages. "They're still warm!"

"I won't 'ave to eat yer, now."

"Cooper! Walsh!" An irate voice came over the radio. "Are you there?"

Quickly, Cooper reached through the open window and took up the mike. "Sarge?"

"Where've yer been?"

"Checkin' out a report, Sarge. The escaped convict..."

"Escaped convict? What escaped convict? Look, will you two wazzocks get along to Top Lane? There's a little fella and this big blonde, stuck inside a couple of beer-barrels. Just rolled down the 'ill. They're gonna need some help."

"We're on it, Sarge." Cooper saluted, even though it was only a Sergeant, who couldn't see him.

Walsh's eyes widened in distrust.

"No convict?"

"Nope."

"You don't think there's a chance that old guy was takin' the wee-wee?"

Cooper looked back towards the forest.

"Let's never speak of this again?"

Walsh grinned. "Speak of what?"

Solemnly, the two coppers shook hands.

"Now," said Cooper. "Let's get back to the matter in 'and."

"What, the two barrels in Top Lane?"

"No, you numpty. Them bananas."

Contented once again, Walsh went and fetched the sugars and syrups, while Cooper started to unwrap the foil packages. Walsh opened the glove compartment in the front of the car, and found a couple of spoons.

The invisible convict had already faded from their minds...