Dream Assassin. Dreamwalker, #2.5

A prequel novella to the Dreamwalker sagaDirk is a mercenary with a very special skill set-he can kill people by entering their dreams. When a duke's daughter is kidnapped, Dirk is hired to rescue the girl and punish those responsible for taking her. A good assassin does the job without getting emotionally involved, but this mission doesn't end up so straight forward. Dirk discovers the kidnappers have their hands in an even more heinous business, and that the local authorities are sanctioning it.
He's never given much thought to right and wrong, only on how much he was being paid. But this time he might just have to set aside the indifferent, professional soldier.and met out justice of his own.