Death on an Autumn River — I.J. Parker

On a river journey to Naniwa to unmask officials selling information to pirates, Akitada witnesses the recovery of a body. The image of the drowned child prostitute follows him as his own problems and disasters multiply. Someone is sabotaging his investigation. His young clerk disappears, Akitada is attacked by two thugs, and armed men brutalize his family in the capital. When Tora joins his master, they both fall into the hands of the pirates and must fight a battle to the death to escape. But ultimately it is the tragic story of the dead girl that will haunt Akitada most.