The Sword of Damascus — Richard Blake

Murderous intrigue brings Aelric -- Blake's engaging, murderous antihero -- to Damascus as the triumphant Muslim caliphate sweeps up from Arabia to threaten Constantinople itself. Aelric knows the secrets behind Greek Fire -- the flame-throwers that have kept what is left of the once-mighty Roman empire safe until now -- and he has very little choice about sharing them with the new rulers. Or so they think, for Aelric has not lost any of the cunning and courage that have kept him alive.