It is one of the great love stories of history, and one of its most successful political partnerships.

Catherine the Great was a woman of notorious passion and imperial ambition, perhaps the greatest of the Romanovs. Prince Potemkin - wildly flamboyant and sublimely talented - was the love of her life and her co-ruler. Together they seized Ukraine and Crimea and founded cities such as Sebastopol, defining the Russian empire to this day. Their affair was so tumultuous they negotiated an arrangement to share power, leaving Potemkin free to love his beautiful nieces, Catherine her young male favourites. But these 'twin souls' never stopped loving each other.

Drawing on their intimate letters and vast new research from St Petersburg to Odessa, Simon Sebag Montefiore's enthralling, much-acclaimed biography restores these imperial partners to their rightful place as titans of their age.