The Stones of Kyudaizu
Some *thing* has killed the lord and stolen his face
Shiba Tametsu was a Phoenix bushi and lord of some renown, as well as a close servant of the phoenix Elemental Council
He issued invitations to ten samurai of various clans to attend him at his home in the northern Phoenix lands, with little explanation as to why. As it turned out, he was acting on behalf of his father, the monk Yono.
On the day Yono was killed, Tametsu just disappeared from his castle. A servant found a body that he identified as the real Tametsu: he had been dead for several days and someone or something was impersonating him the whole time.