Gruen's first two novels, Riding Lessons and Flying Changes, both enjoyed moderate critical success. Her third release, Water for Elephants was published by Algonquin Publishing.  Water for Elephants spent 12 weeks on the New York Times hardcover fiction best-seller list and sold 248,000 copies. The movie rights were optioned to Andrew R. Tennenbaum, a co-producer of the Jason Bourne spy movies, in a deal worth more than $1 million if the movie is made.