According to The Hollywood Reporter, Universal Pictures, along with Hanks' Playtone production company, have optioned the film rights to In the Garden of Beasts: Love, Terror, and an American Family in Hitler's Berlin.  Hanks will produce along with Playtone partner Gary Goetzman, though the actor is considering starring in the potential film, as well.  That decision would likely depend on the eventual screenplay and Hanks' schedule.

If he does star, Hanks would play William E. Dodd, the Chicago professor who became America's very first ambassador to Hitler's Germany.  The amiable diplomat brought his wife, son, and daughter Martha to Berlin, where Martha, thrilled by pomp and circumstance, engages in a series of affairs with members of the Third Reich and even a Soviet spy. 

At first entranced by Berlin, over the course of a year, Dodd became increasingly alarmed and horrified by escalating violence, consistent censorship, and evidence of Hitler's brutal ambitions.

Larson has proven himself a popular crafter of propulsive, fascinating historical narratives.  His earlier bestseller, The Devil in the White City: Murder, Magic, and Madness at the Fair that Changed America, has been in development for years.  That project is currently in the works with producer Leonardo DiCaprio at his Appian Way production company.  The book tells the tale of the 1893 World's Fair in Chicago, laying out the parallel stories of Daniel Burnham, the architect overseeing the fair's construction, and H.H. Holmes, a charming serial killer.  There's also a whole lot of historical incident covered, including the fair's introduction of the world's first Ferris Wheel.