Chaos follows the abdication of the Tsar, and it is into this chaos that Lenin returns from exile. The programme opens with a series of telegrams from the German foreign ministry which reveal that Berlin saw Lenin as a 'secret weapon', a 'dangerous virus' that would foment revolution forcing Russia to withdraw from the war, and so the Germans put him on the legendary sealed train bound for St Petersburg.

But Lenin was most certainly not in control. No one was in control. Tsarism had collapsed but the revolutionaries were far from united. The Provisional Government was trying to create Russia's first western style law-governed state: their "liberal idealism was impeccable," muses Martin Sixsmith, "but the middle of a world war with revolutionary chaos on the streets was not the easiest moment to introduce democracy."

The opposition was divided between the Mensheviks who wanted to go through a phase of capitalist democracy before true revolution ushered in the nirvana of socialism. The Bolsheviks, at that stage minor players, had more idea of what they wanted to destroy than what they wanted to create. But Lenin seized the moment: "All power to the soviets!" was his dramatic conclusion that has resonated through Russian history. He was already plotting a Bolshevik coup to take control and boldly promised Land, Peace, Bread and Freedom. This gave him the popular support he needed to have a real chance of taking power.

But then he ran away. Sixsmith draws on comments by Nikolai Valentinov, a friend of Lenin, which hint at a manic depressive side to Lenin's character to explain it. It puts things on hold, the Bolsheviks go underground, but by October, the pressure for change was unstoppable.

Historical Consultant: Professor Geoffrey Hosking

Producers: Adam Fowler & Anna Scott-Brown

A Ladbroke Production for BBC Radio 4.