Bea has been afraid of water ever since her little brother was taken by the flood. Her father, Karl Klingert, has completely devoted himself to creating the world’s first atmospheric diving suit. Soon, the suit will be presented to the public for the first time. If it goes well, Klingert will win a grant and move with his family to England. Bea thinks her brother is playing hide-and-seek and so will never find them if they leave. She believes the diving suit is a monster that has possessed her father. With the help of a new friend – Peter, a young scamp from the riverside – Bea tries to destroy the monster before her family leaves the city of Wrocław forever.