When they got off the train they borrowed bicycles to ride along the canal towpath until they met up with the search party. Harris, ten years older than Bloggs and fifty-five pounds heavier, found the ride a strain.

They met a section of the search party under a railway bridge. Harris welcomed the opportunity to get off the bicycle. "What have you found?" he said. "Bodies?"

"No, a boat," said a policeman. "Who are you?"

They introduced themselves. A constable stripped to his underwear was diving down to examine the vessel. He came up with a bung in his hand. Bloggs looked at Harris. "Deliberately scuttled?"

"Looks like it." Harris turned to the diver. "Notice anything else?"

"She hasn't been down there for long, she's in good condition, and the mast has been taken down, not broken."

Harris said, "That's a lot of information from a minute under water."

"I'm a weekend sailor," the diver said. Harris and Bloggs mounted their cycles and moved on.

When they met up with the main party, the bodies had been found.

"Murdered, all five," said the uniformed inspector in charge. "Captain Langham, Corporal Lee, and Privates Watson, Dayton and Forbes. Dayton's neck was broken, the rest were killed with some kind of a knife. Langham's body had been in the canal. All found together in a shallow grave. Bloody murder." He was quite shaken.

Harris looked closely at the five bodies, laid out in a line. "I've seen wounds like this before, Fred," he said. Bloggs looked closely. "Jesus Christ, it looks like-"

Harris nodded. "Stiletto."

The inspector said in astonishment, "You know who did it?"

"We can guess," Harris said. "We think he's killed twice before. If it's the same man, we know who he is but not where he is."

"What with the restricted area so close," the inspector said, "and Special Branch and M15 arriving on the scene so quick, is there anything else I need to know about this case?"

Harris answered, "Just that you keep very quiet until your chief constable has talked to our people."

"Found anything else, inspector?" Bloggs asked.

"We're still going over the area, and in ever-widening circles; but nothing so far. There were some clothes in the grave." He pointed. Bloggs touched them gingerly; black trousers, a black sweater, a short black leather jacket, RAF-style. "Clothes for night work," Harris said.

"To fit a big man," Bloggs added.

"How tall is your man?"

"Over six foot."

The inspector said, "Did you pass the men who found the sunken boat?"

"Yes," Bloggs frowned. "Wbere's the nearest lock?"

"Four miles upstream."

"If our man was in a boat, the lock-keeper must have seen him, mustn't he?"

"Must have," the inspector agreed.

Bloggs said, "We'd better talk to him." He returned to his bicycle.

"Not another four miles," Harris complained.

"Work off some of those Sunday dinners," Bloggs told him.

The four-mile ride took them most of an hour. The towpath was made for horses, not wheels, and it was uneven, muddy, and mined with loose boulders and tree roots. Harris was sweating and cursing by the time they reached the lock.

The lock-keeper was sitting outside his little house, smoking a pipe and enjoying the mild afternoon air. He was a middle-aged man of slow speech and slower movements. He regarded the two cyclists with some amusement.

Bloggs spoke, because Harris was out of breath. "We're police officers," he said.

"Is that so?" said the lock-keeper. "What's the excitement?" He looked as excited as a cat in front of a fire.

Bloggs took the photograph of Die Nadel out of his wallet and gave it to the man. "Have you ever seen him?"

The lock-keeper put the picture on his lap while he held a fresh match to his pipe. Then he studied the photograph for a while, and handed it back. "Well?" Harris said.

"Aye. He was here about this time yesterday. Came in for a cup of tea. Nice enough chap. What's he done, shown a light after blackout?"

Bloggs sat down heavily. "That clinches it," he said.

Harris thought aloud. "He moors the boat downstream from here and goes into the restricted area after dark." He spoke quietly, so that the lock-keeper would not hear. "When he comes back, the Home Guard has his boat staked out. He deals with them, sails a bit further to the railway, scuttles his boat and… hops a train?"

Bloggs said to the lock-keeper: "The railway line that crosses the canal a few miles downstream-where does it go?"

"London."

Bloggs said, "Oh, shit."

Bloggs got back to the War Office in Whitehall at midnight. Godliman and Billy Parkin were there waiting for him. Bloggs said, "It's him, all right," and told them the story.

Parkin was excited, Godliman just looked tense. When Bloggs had finished, Godliman said: "So now he's back in London, and we're looking for, in more ways than one, a needle in a haystack again." He was playing with matches, forming a picture with them on his desk. "Do you know, every time I look at that photograph I get the feeling I've actually met the damn fellow."

"Well, think, for God's sake," Bloggs said. "Where?"

Godliman shook his head in frustration. "It must have been only once, and somewhere strange. It's like a face I've seen in a lecture audience, or in the background at a cocktail party. A fleeting glimpse, a casual encounter. When I remember it probably won't do us any good."

Parkin said, "What's in that area?"

"I don't know, which means it's probably highly important," Godliman said.

There was a silence. Parkin lit a cigarette with one of Godliman's matches. Bloggs looked up. "We could print a million copies of his picture; give one to every policeman, ARP warden, member of the Home Guard, serviceman, railway porter; paste them up on boardings and publish them in the papers…"

Godliman shook his head. "Too risky. What if he's already talked to Hamburg about whatever he's seen? If we make a public fuss about the man they'll know that his information is good. We'd only be lending credence to him."

"We've got to do something."

"We'll circulate his picture to police officers. We'll give his description to the press and say he's just a conventional murderer. We can give the details of the Highgate and Stockwell murders, without saying that security is involved."

Parkin said, "what you're saying is, we have to fight with one hand tied behind our back."

"For now anyway."

"I'll start the ball rolling with the Yard," Bloggs said. He picked up the phone.

Godliman looked at his watch. "There's not much more we can do tonight, but I don't feel like going home. I shan't sleep."

Parkin stood up. "In that case, I'm going to find a kettle and make some tea." He went out.

The matches on Godliman's desk made a picture of a horse and carriage. He took away one of the horse's legs and lit his pipe with it. "Have you got a girl, Fred?" he asked conversationally.

"No."

"Not since?"

"No."

Godliman puffed at his pipe. "There has to be an end to bereavement, you know."

Bloggs made no reply.

Godliman said, "Look, perhaps I shouldn't talk to you like a Dutch uncle. But I know how you feel; I've been through it myself. The only difference was that I didn't have anyone to blame."

"You didn't remarry," Bloggs said, not looking at Godliman.

"No, and I don't want you to make the same mistake. When you reach middle age, living alone can be very depressing."

"Did I ever tell you they called her Fearless Bloggs?"

"Yes, you did."

Bloggs finally looked at Godliman. "Tell me, where in the world will I find another girl like that?"

"Does she have to be a hero?"

"After Christine…"

"England is full of heroes, Fred."

At that moment Colonel Terry walked in. "Don't get up, gentlemen. This is important, listen carefully. Whoever killed those five Home Guards has learned a vital secret. There's an invasion coming, you know that. You don't know when or where. Needless to say, our objective is to keep the Germans in that same state of ignorance. Most of all, about where the invasion will come. We have gone to some extreme lengths to ensure that the enemy be misled in this matter. Now, it seems certain, he will not be if their man gets through. He has, it is definitely established, found out our deception. Unless we stop him from delivering his news, the entire invasion-and therefore, one can safely say, the war-is compromised. I've already told you more than I wanted to, but it's imperative that you understand the urgency and precise consequences of failure to stop the intelligence from getting through." He did not tell them that Normandy was the invasion site, nor that the Pas de Calais via Eeast Anglia the diversionary one, though he realised Godliman would surely conclude the latter once he had debriefed Bloggs on his efforts to trail the murderer of the Home Guardsmen.