In the midst of the Great Depression, Jacob Jankowski, a young Polish American veterinary student, loses his parents in a tragic accident. With his dreams of completing his degree shattered, he takes to the rails in search of a new life. Fate leads him to a traveling circus run by the charismatic but tyrannical ringmaster August. Jacob, with his veterinary skills, soon finds work caring for the animals, which are the heart of the show. Among these animals is Rosie the elephant, an untrainable but gentle giant who becomes the center of Jacob's responsibilities.

Jacob forms a close bond with Marlena, August's wife and the star performer, who adores Rosie just as much as he does. As Jacob becomes more ingrained within the circus community, tensions rise with the unpredictable and often brutal August. His growing feelings for Marlena and his dedication to Rosie's well-being put him on a collision course with his volatile boss, leading to life-changing decisions that shape their destinies.