In Author Under Sail: The Imagination of Jack London, 1902-1907, Jay Williams explores Jack London's necessity to illustrate the inner workings of his vast imagination. In this second installment of a three-volume biography, Williams captures the life of a great writer expressed though his many creative works, such as The Call of the Wild and White Fang, as well as his first autobiographical memoir, The Road, some of his most significant contributions to the socialist cause, and notable uncompleted works. During this time, London became one of the most famous authors in America, perhaps even the author with the highest earnings, as he prepared to become an equally famous international writer.

Author Under Sail documents London's life in both a biographical and writerly fashion, depicting the importance of his writing experiences as his career followed a trajectory similar to America's from 1876 to 1916. The underground forces of London's narratives were shaped by a changing capitalist society, media outlets, racial issues, increases in women's rights, and advancements in national power. Williams factors in these elements while exploring London's deeply conflicted relationship with his own authorial inner life. In London's work, the imagination is figured as a ghost or as a ghostlike presence, and the author's personas, who form a dense population among his characters, are portrayed as haunted or troubled in some way.

Along with examining the functions and works of London's exhaustive imagination, Williams takes a critical look at London's ability to tell his stories to wide arrays of audiences, stitching incidents together into coherent wholes so they became part of a raconteur's repertoire. Author Under Sail provides a multidimensional examination of the life of a crucial American storyteller and essayist.