Arthur and the Golden Rope (Brownstone's Mythical Collection 1) by Joe Todd-Stanton

Little Arthur Brownstone is the town oddity, until he is tasked with defeating the horrendous giant wolf Fenrir, who is terrorizing the Icelandic countryside and has extinguished the warming fire that keeps Arthur's town thriving. Join Arthur on this journey through Norse mythology as he meets Thor, defeats Fenrir, and becomes a legend in his own right--the first in a series about the adventuring Brownstone family as they explore folklore from around the world.