At 2.13am on 16 December 1942, a German spy dropped from a Focke-Wulf reconnaissance plane over Cambridgeshire. His parachute opened and he floated down. His nose bled copiously. The spy was well equipped. He wore British-issue army landing boots and helmet. In his pocket was a wallet taken from a British soldier killed at Dieppe four months earlier: inside were two fake identity cards. His pack contained matches impregnated with quinine for “secret writing”, a wireless receiver, a military map, £990 in used notes, a Colt revolver, an entrenching tool, and plain-glass spectacles for disguise. In the turn-up of his right trouser leg was sewn a small Cellophane package containing a single suicide pill of potassium cyanide.

The name of the spy was Edward Arnold Chapman. The British police also knew him as Edward Edwards, Edward Simpson and Arnold Thompson. His German spymasters have given him the codename of Fritz or, affectionately, “Fritzchen” — Little Fritz. The British secret services as yet had no name for him, although the radio traffic concerning “Fritz” had been intercepted and decoded. The Cambridge police had been instructed to be on the lookout for an individual referred to only as “Agent X”.

That night Martha Convine had been woken by a plane droning overhead. Her husband George, foreman of Apes Hall Farm, Ely, was snoring steadily. Martha heard a loud banging on the door. She shook George awake, put on her dressing gown and peered out of the window. “Who is it?” A man’s voice replied: “A British airman.” It was 3.30am. For the past hour, Chapman had been stumbling around in wet celery fields, dazed and still traumatised from his descent.

The figure on the doorstep might have emerged from a swamp. Martha “noticed he had blood on his face”. You can’t be too careful in wartime, so she asked him where his plane was. He gestured vaguely at the countryside: “Across the fields.” Chapman did not start making sense until he was in the kitchen with a cup of tea. He had asked to use the telephone and George, a special constable, dialled the police station at Ely. Chapman reached into his pocket as the police walked in and pulled out a pistol, saying: “I expect the first thing you want is this.” He unloaded it and handed it over.

At police divisional headquarters in Ely, Chapman was stripped, body-searched, issued with new clothing and brought before the Deputy Chief Constable. Chapman was wary: he did not like being inside a police station and he was not in the habit of telling the truth to policemen. “I need to speak to the British secret services, when I will have a very interesting story to tell.”

Two men in civilian clothes arrived in a Black Maria, and Chapman was driven to London. At Ham Common in West London they turned through a gate in a high wooden fence topped by barbed wire and drew up in front of a large, ugly Victorian mansion. Chapman was taken to the basement and locked inside. A man with a monocle opened the door, peered hawkishly at him, said nothing, and then went away. A photographer took his picture. Chapman fought to keep his head up. With a supreme effort he stared into the lens. His face in the photograph is drained by fatigue and stress. But there is something else. Behind the drooping eyelids and stubble lies the very faint trace of a smile.

Lieutenant Colonel Robin “Tin Eye” Stephens, the commander of Camp O20, had a very specialised skill: he broke people. He crushed them, psychologically, into very small pieces and then, if he thought it worthwhile, he would put them back together again. He considered this to be an art. “A breaker is born and not made,” he said. In photographs, Stephens might be the caricature Gestapo interrogator, with the glinting monocle and “vays of making you talk”. He certainly did have ways of making people talk, but they were not the brutal, obvious ways of the Gestapo. Behind the tin eye was an instinctive and inspired amateur psychologist.

Stephens spoke Urdu, Arabic, Somali, Amharic, French, German and Italian, but this multilingualism should not be taken to indicate that he was broad-minded about other races and nations. He was ragingly xenophobic. He disliked “weeping and romantic fat Belgians”, “shifty Polish Jews” and “unintelligent” Icelanders. He also detested homosexuals. Above all, he hated Germans.

In 1940, the government had set up Camp 020 for the interrogation and imprisonment of suspected spies, subversives and enemy aliens in Latchmere House, a gloomy mansion in West London. Colonel Stephens, a Gurkha officer seconded to MI5, terrified his underlings almost as much as the prisoners. He never removed his monocle (he was said to sleep in it). He thought of himself as a master of the interrogative arts. Some colleagues thought he was quite mad. What few disputed was that he was outstanding at his job: establishing the guilt of the enemy spy, extracting vital information, scaring him witless, winning his trust and then, finally, turning him over to MI5 for use as a double agent.

At 9.30am on December 17, Eddie Chapman found himself in Interrogation Room 3 of Camp 020, facing this strange, angry-looking man. “No chivalry. No gossip. No cigarettes . . . a spy in war should be at the point of bayonet.”

A stenographer recorded every word. “Your name is Chapman, is it?”

“Yes, Sir.”

Explore Books

• Book Extracts

• Book Reviews

• Books Group

• Audio Books

Times Recommends

• The 100 Best Books of the Decade
• The Times picks the 50 best paperbacks of 2009
• The conversation: James Ellroy