This rendezvous was timed for either between nine and ten o'clock in the morning or between five and six in the afternoon, and the arrangement was that one went there every day until the other party turned up. If no contact was made for five successive days one went there on alternate days for two weeks. After that one gave up.

Faber got to Leicester Square at ten past nine. The contact was there, in the tobacconist's doorway, with a black-bound Bible under his arm, pretending to shelter from the rain. Faber spotted him out of the corner of his eye and hurried past, head down. The man was youngish, with a blond moustache and a well-fed look. He wore a black double-breasted raincoat, and he was reading the Daily Express and chewing gum. He was not familiar.

When Faber walked by the second time on the opposite side of the street, he spotted the tail. A short, stocky man wearing the trenchcoat and trilby hat beloved of English plainclothes policemen was standing just inside the foyer of an office building, looking through the glass doors across the street to the man in the doorway.

There were two possibilities. If the agent did not know he had been followed, Faber had only to get him away from the rendezvous and lose the tail. However, the alternative was that the agent had been captured and the man in the doorway was a substitute, in which case neither he nor the tail must be allowed to see Faber's face.

Faber assumed the worst, then thought of a way to deal with it.

There was a telephone booth in the Square. Faber went inside and memorised the number. Then he found I Kings 13 in the Bible, tore out the page, and scribbled in the margin, "Go to the phone booth in the Square."

He walked around the back streets behind the National Gallery until he found a small boy, aged about ten or eleven, sitting on a doorstep throwing stones at puddles.

Faber said, "Do you know the tobacconist in the Square?"

"Yerst."

"Do you like chewing gum?"

"Yerst."

Faber gave him a page torn from the Bible. "There's a man in the doorway of the tobacconist's. If you give him this he'll give you some gum."

"All right," the boy said. He stood up. "Is this geezer a Yank?"

"Yerst," Faber said.

The boy ran off. Faber followed him. As the boy approached the agent, Faber ducked into the doorway of the building opposite. The tail was still there, peering through the glass. Faber stood just outside the door, blocking the tail's view of the scene across the street, and opened his umbrella. He pretended to be struggling with it. He saw the agent give something to the boy and walk off. He ended his charade with the umbrella and walked in the direction opposite to the way the agent had gone. He looked back over his shoulder to see the tail run into the street, looking for the vanished agent.

Faber stopped at the nearest telephone and dialled the number of the booth in the Square. It took a few minutes to get through. At last a deep voice said, "Hello?"

"What is today's chapter?" Faber said.

"One Kings thirteen."

"Most inspiring."

"Yes, isn't it."

The fool has no idea of the trouble he's in, Faber thought. Aloud he said, "Well?"

"I must see you."

"That is impossible."

"But I must!" There was a note in the voice that Faber thought edged on despair. "The message comes from the very top. Do you understand?"

Faber pretended to waver. "All right, then. I will meet you in one week's time under the arch at Euston Station at 9 A.M."

"Can't you make it sooner?"

Faber hung up and stepped outside. Walking quickly, he rounded two corners and came within sight of the phone booth in the Square. He saw the agent walking in the direction of Piccadilly. There was no sign of the tail. Faber followed the agent.

The man went into Piccadilly Circus underground station, and bought a ticket to Stockwell. Faber immediately realised he could get there by a more direct route. He came out of the station, walked quickly to Leicester Square, and got on a Northern Line train. The agent would have to change trains at Waterloo, whereas Faber's train was direct; so Faber would reach Stockwell first, or at the worst they would arrive on the same train.

In fact Faber had to wait outside the station at Stockwell for twenty-five minutes before the agent emerged. Faber followed him again. He went into a café.

There was absolutely nowhere nearby where a man could plausibly stand still for any length of time: no shop windows to gaze into, no benches to sit on or parks to walk around, no bus stops or taxi ranks or public buildings. Faber had to walk up and down the street, always looking as if he were going somewhere, carrying on until he was just out of sight of the café, then returning on the opposite side, while the agent sat in the warm steamy café drinking tea and eating hot toast.

He came out after half an hour. Faber tailed him through a succession of residential streets. The agent knew where he was going but seemed in no hurry. He walked like a man who is going home with nothing to do for the rest of the day. He did not look back and Faber thought, Another amateur.

At last he went into a house: one of the poor, anonymous, inconspicuous lodging houses used by spies and errant husbands everywhere. It had a dormer window in the roof. That would be the agent's room, high up for better wireless reception. Faber walked past, scanning the opposite side of the street.

Yes-there. A movement behind an upstairs window, a glimpse of a jacket and tie, a watching face withdrawn. The opposition was here too. The agent must have gone to the rendezvous yesterday and allowed himself to be followed home by MI5, unless, of course, he was MI5.

Faber turned the corner and walked down the next parallel street, counting the houses. Almost directly behind the place the agent had entered there was the bomb-damaged shell of what had been a pair of semi-detached houses. Good.

As he walked back to the station his step was springier, his heart beat a shade faster, and he looked around him with bright-eyed interest. It was good. The game was on.

He dressed in black that night: a woollen hat, a turtleneck sweater under a short leather flying jacket, trousers tucked into socks, rubber-soled shoes all black. He would be almost invisible; for London, too, was blacked out.

He cycled through the quiet streets with dimmed lights, keeping off main roads. It was after midnight, and he saw no one. He left the bike a quarter of a mile away from his destination, padlocking it to the fence in a pub yard.

He went, not to the agent's house, but to the bombed-out shell in the next street. He picked his way carefully across the rubble in the front garden, entered the gaping doorway, and went through the house to the back. It was very dark. A thick screen of low cloud hid the moon and stars. Faber had to walk slowly with his hands in front of him. He reached the end of the garden, jumped over the fence, and crossed the next two gardens. In one of the houses a dog barked for a moment.

The garden of the lodging house was unkempt. Faber walked into a blackberry bush and stumbled. The thorns scratched his face. He ducked under a line of washing-there was enough light for him to see that.

He found the kitchen window and took from his pocket a small tool with a scoop-shaped blade. The putty around the glass was old and brittle, and already flaking away in places. After twenty minutes' silent work he took the pane out of the frame and laid it gently on the grass. He shone a flashlight through the empty hole to make sure there were no noisy obstacles in his way, opened the catch, raised the window, and then climbed in.

The darkened house smelled of boiled fish and disinfectant. Faber unlocked the back door-a precaution for fast exit-before entering the hall. He flashed his pencil light on and off quickly, once. In that instant of light he took in a tiled hallway, a kidney table he must circumvent, a row of coats on hooks, and a staircase, to the right, carpeted. He climbed the stairs silently.