Olaf the Viking by Martin Conway
Olaf is desperate to find his father. It's been a long time since he disappeared, and it could be Olaf's big chance to be a hero. So when his uncle makes it clear that he is more interested in carousing, marauding, and pillaging than in finding his long-lost brother, Olaf decides to take matters into his own hands. With the help of a strangely-gifted slave named Loki, a magical war-hammer, and two barmy ravens, Olaf sets off to adventure! Join Olaf's hilarious and spectacular search in this fast-paced tale of Viking derring-do.