Thorgal: The Scarlet Fire (Thorgal #27)

Thorgal has failed. Despite all his efforts, he came up short in his attempt to save his son Aniel, and was forced to look on as sorcery transformed the young, mute boy into a teenager with terrible powers: the reincarnation of the Master of Red Magic. Our Viking hero, however, is convinced there is still a chance, and isn't yet ready to give up. But many threats are converging, from within the city and from afar, and the stakes may in fact be much higher than Thorgal imagined ...