Catherynne M. Valente 
Deathless [EPUB ebook] 

A handsome young man arrives in St Petersburg at the house of Marya Morevna. He is Koschei, the Tsar of Life, and he is Marya’s fate. For years she follows him in love and in war, and bears the scars. But eventually Marya returns to her birthplace – only to discover a starveling city, haunted by death. Deathless is a fierce story of life and death, love and power, old memories, deep myth and dark magic, set against the history of Russia in the twentieth century. It is, quite simply, unforgettable.