Guiamo Durmius Stolo is an orphan whose uncle and aunt abandon him because of lack of money and food. A man named Calidius finds and raises him, and teaches him how to fish. Calidius soon learns of Guiamo's intelligence and creativity after Guiamo builds a trap for fish. Calidius sends Guiamo to his friend, Gabinius, to teach Guiamo furthermore. Gabinius teaches Guiamo hunting, letters, numbers, etc. Gabinius learns of a prophecy that connects with Guiamo and finds out that Guiamo is the son of Mars. He acquires Mars' original spear, Lúin.

Ten-year-old Guiamo, recently orphaned and abandoned by his impoverished uncle, approaches an elderly fisherman, Calidius, in hopes of obtaining food and shelter. When the weathered seaman takes the boy in, however, Guiamo's destiny is altered forever.

In the time of Rome, Guiamo Durmius Stolo - just another ordinary Roman boy - is abandoned by his uncle in Gaul. Now alone, Guiamo begins to wander aimlessly on the road, heading to a destination he does not know. After wandering for a while, he meets a fisherman who takes him in, teaching him the ways of fishing, and eventually recognizes the talent the boy possessed. After some time has passed, he sends Guiamo once more on the road, but this time to a friend who will teach Guimo even more than the fisherman could.