How could a barely literate peasant from Siberia determine the fate of the world? Undoubtedly, the so-called ‘mad monk’ Rasputin bewitched Tsar Nicholas II and his wife, Alexandra. Yet their strange and scandalous relationship conceals a riddle, one that casts an intriguing light on the controversial ‘great man’ theory of history.

Rasputin was a devoted monarchist, not a revolutionary. He had no official position, no forces at his command. Nevertheless, he contributed more to the fall of the Romanov dynasty than any other individual. So demoralised was the Tsarist officer corps by stories of corruption, to say nothing of the rumours of his debauchery with the Empress – and even her daughters – that when the February Revolution broke out, not a sword was raised in defence of the regime.

Just as Rasputin cast a spell over the Romanovs, his legend has bewitched historians. More than a century later, we still fail to comprehend fully the collapse of the greatest autocracy on Earth. Was there any truth to the wild tales that brought down the empire? Or was his true legacy an unsettling lesson on the potency of myth?