Rokka: Braves of the Six Flowers Vol. 4 (manga)

It all comes down to this: Adlet's last chance to expose the seventh! If he can't figure out who the traitor is in time, his life will be forfeit. He'll have to pull out all the stops-- and accept a little timely help from an unlikely ally-- to save the day. All will be revealed in this final volume of 'Rokka!