Four-year-old Romochka is left alone in a dark, empty Moscow apartment. After a few days, hunger drives him outside, where he sees a large, yellow dog loping past and follows her to her lair on the outskirts of the city. During the seasons that follow, Romochka changes from a boy into something far wilder. He learns to see in the dark, attack enemies with tooth and claw, and understand the strict pack code. But when he begins to hunt in the city, the world of human beings, it is only a matter of time before the authorities take an interest.