When Germany invades Poland, Luftwaffe bombers devastate Warsaw and the city's zoo along with it. With most of their animals killed, or stolen away to Berlin, zookeepers Jan and Antonina Zabinski begin smuggling Jews into the empty cages. As the war escalates Jan becomes increasingly involved in the anti-Nazi resistance. Through the ever-present fear of discovery, Antonina must keep her unusual household afloat, caring for both its human and animal inhabitants - otters, a badger, hyena pups, lynxes - as Europe crumbles around them.