Water for Elephants by Sara Gruen

As a young man, Jacob Jankowski was tossed by fate onto a rickety train that was home to the Benzini Brothers Most Spectacular Show on Earth.It was there that he met Marlena, the beautiful equestrian star married to August, the charismatic but twisted animal trainer. And he met Rosie, an untrainable elephant who was the great gray hope for this third-rate traveling show. The bond that grew among this unlikely trio was one of love and trust, and, ultimately, was their only hope for survival.