Tom Henighan 
Viking Quest [PDF ebook] 

Fifteen-year-old Rigg, son of Leif Eriksson, loves mystery and adventure. In the early eleventh century, he finds both of these in abundance when his father sails away and leaves him behind in Vinland, the Vikings’ precarious foothold on the wild Newfoundland coast. Soon, rigg makes an amazing discovery. The Vikings aren’t alone in this alien land. But who inhabits it with them? Demons, giants, or another human tribe — one that equals the Norse invaders in skill and bravery?