In the middle of the Cold War, the German journalist Richard Sorge, who had worked as a deep-cover Russian military intelligence officer (codenamed Ramsay) in Nazi Germany and Japan, was the most celebrated figure in the USSR’s pantheon of dead intelligence heroes. In 1964, twenty years after Sorge had been hanged in Tokyo as a Soviet spy, he was posthumously made a Hero of the Soviet Union and he was further honoured on the first postage stamps issued in the 20th century to commemorate a spy. No Kim Philby postage stamp was issued until 1990, and he was never made a Hero of the Soviet Union.

Sorge, writes Owen Matthews in the first sentence of his introduction, ‘was a bad man who became a great spy – indeed one of the greatest spies who ever lived’. Within a few pages, it is clear that An Impeccable Spy is going to be a very good read. But the claim that Sorge was ‘one of the greatest spies who ever lived’ is already looking dubious.

Sorge achieved his biggest intelligence successes on the eve and in the first two years of the Second World War while living in Tokyo, where he became a trusted adviser of the German ambassador, General Eugen Ott, and also seduced his wife. In addition to providing important intelligence on Germany’s preparations for an invasion of Russia, thanks to Ott’s misplaced confidence in him, Sorge was also able to keep Moscow informed about the shifting priorities of Japanese policy. He was helped in this by members of a spy ring that included Hotsumi Ozaki, a confidant of the leading statesman Fumimaro Konoe.

The fact that he maintained his cover until October 1941, when he was finally arrested by the Japanese authorities, owed more to luck than judgement. ‘Sorge’, writes Matthews, ‘was both an idealistic communist and a cynical liar’, as well as ‘a pedant, a drunk and a womaniser’. When drunk, as he frequently was, he crashed cars and motorcycles and proclaimed his deep admiration for Stalin. He was driven by such ‘a profound compulsion to deceive’, Matthews concludes, that ‘perhaps he even lied to himself’.

For all Sorge’s talents, An Impeccable Spy seems an odd title for a biography of him. Better than any previous biographer, Matthews lays bare the absurdity of Sorge’s narcissism. ‘Do you know what Sorge is?’ he asked Hanako, his chief Japanese mistress, two months before his arrest. ‘Sorge is a God … God is always a man … People need more Gods … Do you know what Sorge has done? I have arranged that the Japanese government will be defeated soon.’ He spent the last night before his arrest sleeping with Frau Ott, probably boasting about his godlike qualities.

The high point of Sorge’s espionage career in Tokyo was his report to Moscow on 30 May 1941 that Hitler was making final preparations for an attack on Russia: ‘Ott 95% certain that war will commence.’ Hitler’s unshakeable belief in Slav racial inferiority led him to believe that the Wehrmacht would be victorious before winter set in. But Stalin would have none of it, convinced that Hitler was not planning to invade. Sorge’s wholly accurate intelligence on German invasion plans merely seemed to prove to Stalin that the man was a fraud – a lying ‘shit who has set himself up with some small factories and brothels in Japan’.

Speaking truth to power was never more difficult than in the case of Stalin. The few who dared to tell the Soviet tyrant what he did not want to hear put not only their careers but also their lives at risk. The main blame for the catastrophic failure to foresee the German surprise attack on 22 June belongs to Stalin himself. He chose to ignore a series of accurate warnings, then denounced those who provided them.

Six days after his arrest, Sorge suddenly confessed. ‘I have never been defeated since I became an international communist,’ he declared. ‘But now I am beaten by the Japanese police.’ The Japanese prosecutor reported, ‘We were all surprised and aghast at Sorge’s behaviour. He completely broke down before us. He was a pathetic picture of … an emotionally defeated person.’

Remarkably, Sorge gradually recovered his composure, despite being denied the alcohol on which he had become dependent. A German embassy translator who took down his last will and testament in 1943 found him looking well after two years of enforced sobriety and giving the impression of ‘a man who is proud to have accomplished a great work and is now ready to leave the scene of his accomplishments’. At his execution on 7 November 1944, Sorge impressed the prison guards with his bravery. As his arms and legs were bound and the noose placed around his neck, he said loudly in Japanese, ‘Red Army! International Communist Party! Soviet Communist Party!’

Sorge died without knowing that before his arrest Moscow already had a Japanese intelligence source that was even more useful than his Tokyo spy ring. The intelligence that did most to persuade Stalin that the Japanese would not attack the USSR after the German invasion came not from spies but from codebreakers, who cracked the main Japanese diplomatic cipher. Sergei Tolstoy, chief Japanese specialist in the cipher department of the NKVD, became the most decorated Soviet cryptanalyst of the war.

The role of cryptanalysis in Soviet intelligence operations in Japan is an omission in Owen Matthews’s book, but his study of Sorge’s extraordinary, though far from impeccable, espionage is vivid and revealing.