Jacob Jankowski is just a normal, young adult that is studying at college to become a vet. However, everything changes when both his parents died. Homeless and without any money, Jacob takes his chances by jumping onto a passing train. There he is welcomed as a vet for the animals. As the days go on, he's become great friends with August, a circus boss, and his wife Marlena, a performer. Slowly Jacob begins to fall in love with Marlena and hate August for his cruelty to the animals and other men. Meanwhile, the circus buys an elephant named Rosie, who at first seemed stupid and worthless, was soon a main act of the show, thanks to Jacob. Then August accuses Jacob and Marlena of having an affair behind his back, which made him go into a madmen state, beating up Jacob and hitting his own wife. Suffering enough of the abuse, Marlena divorces him and Jacob was there immediately to support her. As Uncle Al (overall circus manager) realizes that August is becoming difficult to work with due to his hate for himself because of what he did to Marlena and Jacob, he forces Jacob to try to get Marlena and August back together. However, Jacob doesn’t follow the command, still having affairs with Marlena, but when his two close friends gets 'redlighted', he realizes that Uncle Al was going after him. Luckily enough, a terrible stampede happened on the next circus act, leaving many of the workers homeless, and August and Uncle Al dead. Jacob immediately marries Marlena and decide to join Ringling's circus, where they had their first child. As the story goes, another story unfolding as well - the one with Jacob as ninety or ninety three (it's a debate throughout the book) reflecting on what happened through his life in the circus and his life now, in a nursing home with others of his own age or younger. In the end, even though no one came to visit Jacob and take him to the circus near the senior’s home, Jacob was determined and arrived at the circus on his own. There, he meets the manager of the circus who listens to his story and offers him a job in the circus as a ticket holder, and never does Jacob go back to the nursing home.

After accidentally running away with the circus, a young man finds danger, happiness, love, friendship and his future among the animals.