The Temple of the Dead. Akitada Mysteries, #22

Akitada discovers that his appointment as governor comes with baggage in the person of the prime minister's favorite nephew. Then things turn really ugly. He arrives to find a flooded province, mutinous nobles, and an empty tribunal, the previous incumbent having fled from a hostile population. When the P. M.'s nephew disappears, a frantic search of an abandoned temple turns up a dark and murderous secret.
Murders multiply: a merchant finds his wife's headless body and a man is tortured to death. Add two seductive young women who have a plan of their own and both Akitada's career and marriage are threatened.