The main hall at the Grand Central hotel was abuzz; not least with the protests of three chess players, who were complaining loudly to a hapless organiser (behind whom stood Annie Cartwright, making sure he didn't waver) that they had booked their places to play Spassky weeks ago and had confirmation and everything, so why were they being told now that they were only reserves?

Only one player was conspicuous by his absence as the entries closed, and that was Simon Donaldson.

Meantime, Gene Hunt was sitting behind a chess board looking like a ham sandwich at a bar mitzvah. Sam Tyler had seen Hunt in many different contexts since he had been catapulted back in time to 1973, and rarely if ever had he seen the DCI looking at such a loss.

"The horsey ones are the ones that jump over the others, right?" Hunt muttered to Tyler. Tyler nodded.

"And they're the ones that can't go in a straight line? They make an L shape?"

Another nod.

"Bloody silly game if you ask me," Hunt concluded. "If scrotes like Stevie Deacon are good at it, that's a strike against it far as I'm concerned."

Further down the row of tables Chris Skelton was sitting poring over a little handbook of chess openings. Further down still, Ray Carling's seat was empty; Carling himself was coming across the room from the direction of the hotel bar with a pint of beer in either hand.

"Here you go, guv. Courtesy of the famous grandmaster Whitbread," he grinned as he set one pint next to Gene Hunt. Hunt's hand flashed out to it as quickly as ever a chess player's hand reached out to capture a piece, and he took a long and grateful drink. "God, that's better," Hunt sighed.

Five minutes to the start of the simultaneous tournament. Spectators were starting to fill the public area.

"Never knew chess was so popular," said Hunt, looking around.

"It is, for now," Tyler said. "Won't last."

"Won't it?" Hunt gave Sam Tyler a perplexed look.

Sam gave a shrug, as if to hint that he'd just been pulling a prediction out of the air.

"Come on, genius. Get back to your set and your coffee cup. Spasstik'll be out in a minute." Hunt took another long swig of beer.

The organiser returned to his table at the head of the hall. Annie Cartwright joined him there keeping a watchful eye on the players in front of her. Boris Spassky appeared at his appointed time to the second, to receive a polite but enthusiastic round of applause from the assembled players and spectators. He smiled modestly as he began to walk down the rows of chessboards, making white's first move on each board. Sam Tyler's heart was thumping, and he realised suddenly that it wasn't just because he was poised for action, ready to help foil a threatened crime. He was sitting at a chessboard, about to face one of the best players the world had ever known in 1973; hell, still one of the best players the world had ever known in 2006. Sam was enough of a chess player that he could not help feeling a little mindblown. Of all the things that had happened since he was pitchforked back in time, this was surely one of the oddest. He touched his belt holster to help ground himself. He must not forget that he was here as a police officer, not as a chess player.

Spassky completed his first move on board fifty and began to circle the room again. He played his second move against Tyler; against Hunt, sitting in the seat that should have been given to "Simon Donaldson"; against Carling and against Skelton, against forty-six other players; and around he went again.

After nine moves Gene Hunt stood up with a scowl and looked at the Russian grandmaster opposite him as if he wanted to punch him. Spassky extended a hand, and Hunt took it, without dropping his scowl, and shook it before sitting back down and staring at his checkmated king, unable to believe that he'd been vanquished in such a short space of time.

Move twelve, and Sam Tyler looked at his position thoughtfully. It was a little cramped – Spassky was coming out of the opening with an advantage – but it certainly wasn't lost, at least not yet. Only one piece remained to be developed, his queen's knight, and his last move had made a safe spot for it to come out at last. Making a final mental check, he reached out and grasped the knight.

It was as if by touching the piece, he'd activated some kind of switch. Boris Spassky, standing at another board a few tables away from Sam, flickered out of existence. So did the rest of the room, a few tables at a time, a few people followed by a few more. The big chandeliers in the ceiling went. The audience went. Within seconds only Sam Tyler himself was left, with a chess board in front of him but no opponent, and his queen's knight grasped in the palm of a suddenly clenched fist.

"…sudden activity from Sam… he's actually moved his hand… within minutes of us setting up the chessboard, he reached out and took hold of a piece…" The voice seemed to come from everywhere around him, and yet from nowhere.

Sam jerked his hand open and stared at the black knight, wide-eyed. The voice droned on.

"…may be a simple random muscle movement, so we mustn't get our hopes up too high… brain stem function remains constant… but he's holding the piece firmly…"

"It's not bloody random!" yelped Sam.

The man on the next board looked at Sam Tyler curiously as he sat there rigidly, eyes closed, knight clutched in his raised hand. Then he shrugged. Chess players did some strange things when they were thinking deeply. He'd once stirred his cup of tea with his queen instead of a teaspoon when calculating a combination. He switched his focus away from Tyler and back to the position in front of him, where Spassky seemed about to win a pawn no matter what move Black made to try and prevent it.

Five seconds later his concentration was broken for a second time.

"NOBODY MOVE!"

Another player, further down the line, had jumped up from his seat, scattering chessmen everywhere, and was pointing a gun straight at Boris Spassky. Vaulting over the table, he grabbed Spassky and shoved the gun under his chin.

"ARMED POLICE! EVERYBODY GET DOWN!" Gene Hunt came out of his chair like a partridge disturbed by a beater, and his shout echoed around the hall even more than that of the gunman had.

Screams, shouts and general pandemonium broke out. Chessmen scattered as chess players dived under their tables or ran towards the exits. A shot rang out; another player had pulled a gun, and Ray Carling had drawn his own weapon and fired at the second criminal. Two more men were running in from the direction of the street, both wearing balaclavas. Chris Skelton dived at one and brought him down with a rugby tackle that David Duckham might have been proud of. He cannoned into the second one, whose drawn pistol went off and fired its bullet up into one of the hotel chandeliers, sending bits of shattered crystal everywhere.

Only one man in the room remained motionless. Sam Tyler remained like a statue at his chessboard, eyes screwed shut, black knight still in his hand.