In "Island of Exiles," Heian Period official Sugawara Akitada finds himself ordered to Sado Island, off the coast of Niigata, to investigate the death by poisoning of the exiled Prince Okisada.
Like France's Devil's Island penal colony in more recent times, banishment and exile was a common punishment in 11th-century Japan, and while perhaps more humane than the death penalty, the conditions were harsh and only a lucky few ever returned.
Shipped to Sado in the guise of a nobleman convicted of homicide, Akitada — who is in fact from the Kyoto nobility — hasn't a clue as to how to conduct an undercover investigation, and this inability promptly earns him a brutal beating from a cop right from the get-go.