At first it looked as though the truck would be out of the way by the time the convoy reached it. But the driver obviously did not have the angle of approach quite right, for he pulled forward again, completely blocking the road.

The two motorcycles in front braked to a halt, and Ron drew the van up behind them. One cyclist heaved his machine onto its stand and jumped up on the footplate of the cab to shout at the driver. The truck's engine was revving noisily, and black smoke poured from its exhaust in clouds.

"Report an unscheduled stop," Ron said. "Let's work the routine like the book says."

Max picked up the radio microphone. "Mobile to Obadiah Control."

Ron was looking at the truck. It carried an odd assortment of vehicles. There was an elderly green van with COOPERS FAMILY BUTCHER painted on the side; a crumpled Ford Anglia with no wheels; two Volks-wagen Beetles piled one on top of the other; and, on the upper rack, a large white Australian Ford with a coachline and a new-looking Triumph. The whole thing looked a bit unsteady, especially the two Beetles in a rusty embrace, like a pair of copulating insects. Ron looked back at the cab: the motorcyclist was making signs at the driver to get out of the convoy's way.

Max repeated: "Mobile to Obadiah Control. Come in, please."

We must be quite low, Ron thought, this close to the river. Maybe reception is bad. He looked again at the cars on the transporter, and realized that they were not roped down. That really was dangerous. How far had the transporter traveled with its load of unsecured scrap?

Suddenly he understood. "Give the Mayday!" he yelled.

Max stared at him. "What?"

Something hit the roof of the van with a clang. The truck driver jumped out of his cab onto the motorcyclist. Several men in stocking masks swarmed over the scrap yard wall. Ron glanced in his wing mirror and saw the two motorcyclists behind the van being knocked from their machines.

The van lurched and then, incomprehensibly, seemed to rise in the air. Ron looked to his right and saw the arm of a crane reaching over the wall to his roof. He snatched the microphone from a bemused Max as one of the masked men ran toward the van. The man lobbed something small and black, like a cricket ball, at the windshield.

The next second passed slowly, in a series of pictures, like a film seen frame by frozen frame: a crash helmet flying through the air; a wooden club landing on someone's head; Max grabbing the gear stick as the van tilted; Ron's own thumb pressing the talk button on the microphone as he said "Obadiah Mayd-"; the small bomb that looked like a cricket ball hitting the windshield and exploding, sending toughened glass fragments into the air in a shower; and then the physical blow as the shock wave hit and the quiet darkness of unconsciousness.

Sergeant Wilkinson heard the call sign "Obadiah" from the currency shipment, but he ignored it. It had been a busy morning, with three major traffic hold-ups, a cross-London chase after a hit-and-run driver, two serious accidents, a warehouse fire, and an impromptu demonstration in Downing Street by a group of anarchists. When the call came in he was taking a cup of instant coffee and a ham roll from a young West Indian girl and saying: "What does your husband think about you coming to work with no bra?"

The girl, who had a large bust, said: "He doesn't notice," and giggled.

Constable Jones, on the other side of the console, said: "There you are, Dave, take the hint."

Wilkinson said: "What are you doing tonight?"

She laughed, knowing he was not serious. "Working," she said.

The radio said: "Mobile to Obadiah Control. Come in, please."

Wilkinson said: "Another job? What?"

"I'm a go-go dancer in a pub."

"Topless?"

"You'll have to come along and see, won't you?" the girl said, and she pushed her trolley on.

The radio said: "Mayd-" then there was a muffled bang, like a burst of static, or an explosion.

The grin faded rapidly from Wilkinson's young face. He flicked a switch and spoke into the microphone. "Obadiah Control, come in, Mobile."

There was no reply. Wilkinson called to his supervisor, putting a note of urgency into his voice. "Guvnor!"

Inspector "Harry" Harrison came across to Wilkinson's position. A tall man, he had been running his hands through his thinning hair, and now he looked more distraught than he was. He said: "Everything under control, Sergeant?"

"I think I caught a Mayday from Obadiah, guv."

Harrison snapped: "What do you mean, think?"

Wilkinson had not made sergeant by admitting his mistakes. He said: "Distorted message, sir."

Harrison picked up the mike. "Obadiah Control to Mobile, do you read? Over." He waited, then repeated the message. There was no reply. He said to Wilkinson: "A distorted message, then they go off the air. We've got to treat it as a hijack. That's all I need." He had the air of a man to whom Fate has been not merely unjust but positively vindictive.

Wilkinson said: "I didn't get a location."

They both turned to look at the giant map of London on the wall.

Wilkinson said: "They took the river route. Last time they checked in was at Aldgate. Traffic's normal, so they must be somewhere like, say, Dagenham."

"Great," Harrison said sarcastically. He thought for a moment. "Put out an all-cars alert. Then detach three from East London patrols and send them on a search. Alert Essex, and make sure those idle sods know how much bloody money is in that van. All right, on your bike."

Wilkinson began to make the calls. Harrison stood behind him for a few moments, deep in thought. "We should get a call before too long-someone must have seen it happen," he muttered. He thought a bit more. "But then, if chummy is clever enough to knock the radio out before the boys can call in, he's clever enough to do the job somewhere quiet." There was a longer pause. Finally Harrison said: "Personally, I don't think we stand a sodding chance."

It was going like a dream, Jacko thought. The currency van had been hoisted over the wall and gently set down beside the cutting gear. The four police motorcycles had been tossed aboard the transporter, which had then reversed into the yard. The riders now lay in a neat line, each of them handcuffed hand and foot, and the yard gates were shut.

Two of the boys, wearing goggles over their stocking masks, made a man-sized hole in the side of the currency van while another plain blue van was backed up. A large rectangle of steel fell away, and a uniformed guard jumped out with his hands above his head. Jesse handcuffed him and made him lie down beside the police escort.

The cutting gear was wheeled away rapidly and two more men got into the currency van and began to pass the chests out. They were put straight into the second van.

Jacko cast an eye over the prisoners. They had all been bashed about a bit, but not seriously. All were conscious. Jacko was perspiring under the mask, but he dared not take it off.

There was a shout from the cabin of the crane, where one of the boys was keeping watch. Jacko looked up. At the same time, he heard the sound of a siren.

He looked around. It couldn't be true! The whole idea was that they should knock the guards out before they had time to radio for help. He cursed. The men were looking to him for guidance.

The transporter had backed behind a pile of a tires, so the white motorcycles could not be seen. The two vans and the crane looked innocent enough. Jacko shouted: "Everybody get under cover!" Then he remembered the prisoners. No time to drag them out of the way. His eye lit upon a tarpaulin. He pulled it over the five bodies, then dived behind a skip.

The siren came nearer. The car was traveling very fast. He heard the squeal of tires as it swung under the railway arch, then the scream of the engine as the car touched seventy in third before changing up. The sound got louder; then suddenly the pitch of the siren dropped and the noise began to recede. Jacko breathed a sigh of relief, then heard the second siren. He yelled: "Stay down!"