The three silhouettes appeared from behind a tree and moved swiftly across the road. A few street lamps, plus the quarter moon on this clear night, were providing a small amount of light; however, it was dark enough and quiet enough that the figures were moving unnoticed.

At 1.30 a.m. in this exclusive residential area, the only sound that could be heard was a fox screeching out into the still night. All the dwellings here were large, detached, and unique, and most of them were hidden behind large gates set well back from the quiet road. This wasn't Beverly Hills, this was south-east England, but it could only be described as a very upmarket area; it was inhabited only by the rich and successful.

The human shapes were dark, but it was obvious from their gait that they were three adult males. The trio stopped tight up against the boundary wall of one particular property. Instantly, one crouched down and formed a cup by linking his hands together to act as a support, and the other two, in turn, placed a foot in the cup and effortlessly scaled the wall.

The drop the other side was not long – the same ten foot or so they had just scaled – but as they hit the ground one after the other, they landed on stones, scattering them noisily. One of the men, looking sinister in his balaclava, motioned to the other to stop. Both men froze in their stances, as if they were playing the children's game of statues. However, after ten seconds of no sounds or any lights coming on, the same man waved his arm in the direction of the house, and they both set off across the gravel. Meanwhile, on the other side of the wall, the third man, the human ladder, remained tight up against the brickwork, hidden in the shadows.

The largish house was about twenty years old, with the stony driveway area leading to a double garage away to the left, which created an L shape with the main building. The front door was about twenty yards away, directly across from the place where the men had dropped from the wall. The house was a two-storey structure that, judging by the size, probably had five or six bedrooms. It was brick-built, with a few potted plants dotted around this area for decoration, the only vegetation at the front of the property. There was probably a sizeable rear garden, but in this light it was impossible to see. The intruders headed behind the garage at the left edge of the plot, moved round to the side of the house, and soon found themselves at a back door; this was fully hidden from view by the garage structure and the property's side wall. The men seemed to know exactly where to go.

The second man, also in a balaclava, then set to work on the lock of the back door, which would presumably lead into a kitchen or utility room. He crouched down by the door handle, pulled out a couple of tools from his back pocket, and within what seemed just a few seconds, the door was open. This was clearly not beginner's luck. The modern kitchen door with two locks proved no barrier to this seasoned burglar. There was a split-second pause as the two men stared at each other, waiting for an alarm to start blaring. The relief was visible in the men's eyes when all remained silent. As had been promised to them, there was no alarm.

The men stepped into a deserted kitchen, not quite pitch black but dark all the same. It felt cold, due to the floor tiles and the fact that the heating had probably been off now for a few hours. Again the first man, who seemed to be the leader, instructed his expert burglar companion to wait by the kitchen door simply by holding up his right hand and motioning him to keep still. The man did as he was told.

The leader, a large, well-built man, then stepped out of the kitchen into an empty hallway, gently lit by the moonlight coming in through the two panels of glass in the front door.

"The front door," he thought. The man now had his bearings and knew exactly where in the house he was. More importantly, he knew where he needed to go next. With just the mechanical tick-tock of a small wall clock for company, he noticed the time, 1.35 a.m., and then continued his quiet journey. He walked past two doors, one fully closed and the other wide open – through which he could see a large sofa in a sizeable lounge. He was, however, heading to the end of the hall, towards a third door, one which was slightly ajar.

He very slowly and gingerly pushed the door open to reveal a small room, which was clearly being used as an office. This room was a mess. The man thought to himself that if he could get out of the property unnoticed with the prize he had come to steal, it could actually be some time before the owner was even able to report a robbery. There were bits of paper everywhere: across the desk, on the floor, and also pinned to the wall on several cork notice boards. There were shelves on two sides of the room, and these were literally bursting with books, folders, and document holders in no apparent sequence or logical order. The kitchen and the hallway had seemed spotlessly clean and tidy; however, this room was a complete shambles; dusty and disorganised. This villain was going to have a harder job than he'd imagined finding what he was looking for.

He reached into his dark, lightweight jacket and pulled out a small torch, instantly flicking it on. The extra light it produced showed that the room was in an even worse state than the original negative impression he'd formed by the half light. Had someone already ransacked the room and beaten him to his prize? Had he been double-crossed somewhere, leaving his master plan in tatters? He knew the answer to both of those questions was definitely no, but he did feel slightly less confident of success than he had three minutes ago when he and his companion had so effortlessly gained entry to the property.

He walked over to the desk in the far corner of the room, on which stood a computer, switched off and dusty. He pointed the torch at the desk to reveal the sea of papers and discarded envelopes. There were utility bills, bank statements, and even some good old-fashioned letters, a throwback to the pre-email era. He picked up a small picture from the desk. It showed an elderly man and woman being greeted by a dignitary of some kind. Maybe it was the mayor of their town? Who cared? The man knew the elderly couple were the owners of the property, and he also knew for certain they were upstairs – hopefully fast asleep. Under the balaclava, an evil smirk crossed his face.

He suddenly lifted his gaze towards the door of the study – and froze. A figure stood there. He let out a huge breath of relief as soon as he realised that it was his co-intruder, the master burglar, who had ignored his orders and left the kitchen. The shape stood in the doorway, tapping his wrist as if pointing at a watch, reminding his leader that the operation was taking too long. There was certainly no time to be looking at family photographs.

The leader nodded, put the picture back on the desk, and held up his hand and index finger as if to signal one more minute. After all, he had just spotted what he was looking for. He walked over to the bookcase on the wall to his right, pointed his torch at a shelf, and removed a glass container. He slowly lifted the lid and removed a flat A4 card folder. This was definitely it – he recognised it immediately. He shone the torch on the folder. It read "Battler's Theory: 17 July, 2004". He put the lid back on and placed the empty glass box back on the shelf.

The thief drew a large intake of breath. He knew the only reason why this priceless folder was so poorly protected was that the current custodian thought there wasn't a single person in the world who actually knew it existed, let alone what it contained. He tucked the folder under his arm, motioned to his accomplice to go, and they both headed out of the room, across the hall, and back into the kitchen. It all seemed too easy.

Back in the kitchen, the master burglar picked up a kitchen chair to enable the pair to easily scale the property's perimeter wall again. He then headed for the door. The leader followed him to the door but then unexpectedly stopped, turned, and unleashed another evil grin from inside the mask.

For reasons not yet known to his companion, he flicked the kitchen light on and started to look around the room. Just outside the back door now, the other burglar held his arms out wide, suggesting he was bewildered as to what was going on. The leader simply turned, picked up a large vase from the kitchen work surface and hurled it at the kitchen window, smashing both the glass pane and the vase. The crash of crockery and splintering glass was predictably loud and instantly bought audible movement from upstairs. A neighbour's dog started barking frantically at the same time.

The puzzled look on the eyes of the burglar turned to one of panic, and both men then dashed away from the house and back across the gravel driveway to the wall. They placed the kitchen chair down beside it, and the burglar climbed over the wall first. A quick glance back at the house showed him that several upstairs lights had now come on. An elderly male face could be seen at one of the windows, clearly petrified as he looked down on his driveway to see two masked men leaving his property – two masked men who had clearly just been inside his house.

The lady of the house made the emergency 999 phone call instantly, and as she was speaking to the police, all the elderly man was able to do was stare out of the window. From on top of the wall, the second man turned his head around and looked up at the occupied window to the scared male face. He rolled down the bottom of his balaclava to expose his mouth and expose his sinister smile. With that, he jumped down the other side and joined his two companions, and the three of them ran off into the night. Already a whiter shade of pale, the ageing, frail gentleman collapsed.

Running at a steady pace, the third man put his thumbs up as if to question how the mission had gone. The intruder holding the folder, the leader, gave a thumbs-up in response, but the door-entry expert ripped off his balaclava in disgust and, speaking with a strong French accent, said, "Yeah, everything was perfect until Einstein 'ere deliberately woke ze neighbour'ood," nodding his head in the direction of the leader.

"Look, I know what I'm doing," the leader said sternly and abruptly, despite gasping for breath from the running. "Just stick to the plan. We just need to get back to the hostel in the next five minutes, and we are home and dry," he added in an equally aggressive manner.

"What did you —?" the first man said, coming to a halt and removing his own balaclava, but he was cut short by an "enough" gesture by the leader.

"Five more minutes of running, and we are there," he said, this time with a slightly sympathetic tone, as if realising that with some people, even burglars, aggression may not always be suitable and that a reassuring stance might lead this team of criminals to success tonight.

"And both of you put your masks back on, or the whole plan is ruined," he finished as the trio broke into a run again. Their destination was now in view.

Their masks were all back on as the three men jogged up the steps of a small hostel in the centre of town and let themselves in, to the sounds of an ambulance siren and a police car off in the distance. They were in.

Detective Sergeant David Johnson had been on duty since 10 p.m. when the call came in. This shift was somewhat unoriginally known as the "graveyard shift" because once the pubs had emptied things generally quietened down until the day shift took over.

"Reported break-in, Linfield House, Sandy Lane, south side of Arleswood," announced the duty sergeant, Sergeant Hughes. "Shall I send a squad car?"

Johnson thought for a moment. "Isn't that where old Freddie Leston lives?"

"That's right, Detective Sergeant," added Hughes. "His wife has just reported the burglary, and she has also called for an ambulance."

"That puts a different complexion on things," thought Johnson, concluding that if an ambulance was needed, there might have been violence. "No, I'll go myself. We'd better have some forensic backup also," he said. "And please alert Inspector Hartnell."

"No need for that," said a voice from the doorway. "I'm already here."

Inspector Roger Hartnell and Sergeant Johnson were firm friends, although they were careful to maintain the formality of their ranks when on duty. As they were both in their early forties, and with experience of policing many tough London estates, they found they had a lot in common.

Hartnell, the senior man, was the taller of the two, with the sort of cultured voice that went down well with the wealthy local residents. He had a kind, friendly, handsome face and was respected and trusted in most situations. He was no pushover, though. Underneath the quiet exterior was a steely career policeman, and more than one hardened criminal had made the mistake of taking him for an easy touch. Although not required to wear a uniform in his investigative role, Inspector Hartnell was always immaculately dressed, preferring trousers and a shirt over smart jeans, and today was no different. He had young twin boys and always maintained that they should never see him anything other than looking his best, so he would set a strong example for them.

Sergeant Johnson was also a committed police officer. He was very competent but had never been able to progress beyond his current rank. He was of average height and, although slightly overweight, was fit and healthy. However, he often felt that, despite his exemplary record, he had been overlooked for promotion because of his physical appearance. Hartnell and Johnson had worked together for several years in London and again now in leafy suburbia, and each was totally loyal to the other. They made an excellent team. Hartnell had a reputation for putting gut instinct ahead of routine police work, and Johnson on most occasions ensured his superior office and friend didn't get too carried away.

Within minutes the two officers were on their way to Sandy Lane.

"It's rather worrying that an ambulance has been called to a break-in," mused Hartnell. "I hope neither of the Lestons are badly injured."

"According to Hughes, it was Mrs Leston who reported the break-in," replied his companion, "which suggests that her husband may be the one needing medical help."

"Indeed, Dave," replied Hartnell, calling his colleague by his first name now that they were alone. "It's a shame that he's a doctor in the academic field and not the medical one, or he'd be able to give himself the best possible help."

As the police car approached Linfield House, the officers could see that the gates were open and an ambulance was already on the driveway. A man was standing by the open front door; his coat appeared to have been hastily put on over his dressing gown, which gave him a rather dishevelled look. He looked relieved when he saw the policemen arrive, and he stepped out to greet them.

"Thank goodness you are here," he said breathlessly. "The paramedics are upstairs with Fred."

The inspector went straight into the house and up the stairs. Johnson turned to the man. "You are, sir?" he enquired.

"Andrew Williams. I live next door. I heard a loud smashing sound and general commotion, which set my dog off, so I rushed over to see what was the matter. Mrs Leston let me in."

"OK, Mr Williams," replied the Sergeant. "You did exactly the right thing. If you would like to come in with me now, your presence may be reassuring to the Lestons."

Together the two men went up the stairs, where they joined Inspector Hartnell on the landing. An elderly, frail-looking gentleman was sitting propped up against the wall, with a young paramedic leaning over him. It appeared the old man was just concluding a phone call, to the slight frustration of the medic. A petite grey-haired lady was looking on anxiously, and a second paramedic, a young lady, was comforting her.

"What is your name, sir?" the paramedic asked the frail gentleman the moment he'd finished his phone call.

"Leston. Frederick Leston," replied the gentleman in a rather weak voice.