Young Torbjorn Trofastsonn comes from the clan that makes the most coverted treasure of the Viking Age—blueberry muffins. A single bite of these muffins is enough to cause people to go to war, just for another taste. Torbjorn is a Viking through and through; he's thirteen winters old, larger than most respectable rocks, and most of all, a Buttersmith. That's what he thinks anyway, until a charismatic merchant makes Torbjorn question his place among the muffin-makers. When Torbjorn lets the secret of his clan's muffin recipe slip, he calls doom and destruction down upon his peaceful village and forces his brother Storfjell and his clansmen to do the one thing they are ill-prepared to do: battle for their lives.