Part I leads with a heading which establishes the role of Dr Watson as narrator and sets up the narrative stand-point that the work to follow is not fiction, but fact: "Being a Reprint from the Reminiscences of John H. Watson, MD, Late of the Army Medical Department."
The story flashes back to the Salt Lake Valley (in modern Utah) in 1847, where John Ferrier and a little girl named Lucy, the only survivors of a small party of pioneers, lie down near a boulder to die from dehydration and hunger.
PART I. The Reminiscences of Watson