In 1931, 23-year-old Jacob Jankowski is about to graduate from Cornell University's veterinary program when he learns that his parents died in a car accident, leaving him penniless. Distraught, he hops aboard a passing train, which belongs to the Benzini Brothers Circus. He is hired to care for the circus animals by the owner, Uncle Al, after Uncle Al learns of his veterinary training.
Jacob befriends an equestrian performer named Marlena, who is married to the circus's violent animal trainer, August. Jacob also meets Rosie, an elephant that August struggles to train because she understands only Polish commands. With Jacob's help, Rosie learns incredible tricks and becomes the star of an popular circus act with Marlena.
As Jacob and Marlena grow closer, August's paranoid behavior escalates. After discovering their affair, August brutally attacks them both. Marlena leaves August, but Uncle Al wants them to reconcile for the sake of the show. Jacob and Marlena hatch a plan to escape with Rosie and several other circus workers.