What makes a Stalin? Was he illegitimate? Was his mother whore or saint? Was Stalin a Tsarist agent or Lenin's chief gangster? Was his most notorious heist planned during his stay in London? Was he to blame for his wife's death? If he really missed the 1917 Revolution, how did he emerge so powerful?

Born in poverty, scarred by his upbringing, exceptional in his studies, this charismatic but dangerous boy was hailed as a romantic poet and trained as a priest but found his mission as fanatical revolutionary. He became the mastermind of bank-robberies, protection-rackets, arson, piracy and murder yet he was, uniquely, part-intellectual, part-brigand. Surprisingly, he is also revealed as a scandalously prolific lover, leaving a trail of mistresses (varying from schoolgirls to noblewomen) and illegitimate children.

Here is the arch-conspirator and escape-artist whose brutal ingenuity so impressed Lenin that he made Stalin (with Trotsky) his top henchman. The paranoid underworld of Joseph Conrad-style terrorism was Stalin's natural habitat. Montefiore shows how clannish Caucasian banditry and murderous gangsterism, combined with pitiless ideology, qualified Stalin to dominate the Kremlin – and create the USSR in his flawed image.

Based on massive research and astonishing new evidence in archives from Moscow to Georgia, Young Stalin, companion and prequel to bestselling, prizewinning Stalin: The Court of the Red Tsar, is a chronicle of the Revolution, a pre-history of the USSR – and a fascinatingly intimate biography: this is how Stalin became Stalin.