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. More 'guests' hide inside the Zabinskis's villa, emerging after dark for dinner, socializing and, on rare occasions of calm, piano concerts. They call this refuge from the Nazi occupation 'The House Under a Crazy Star'.
As the war escalates Jan becomes increasingly involved in the anti-Nazi resistance. Ammunition is buried in the elephant enclosure and explosives stored in the animal hospital. Plans are prepared for what will become the Warsaw uprising. 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.