I’ll let the narrator, Sean Cornwell, introduce the story in his own words:
“Sean here. When wolf-riding trolls attack our house, my sister Fiona and I find out the hard way that we’re destined to be heroes. That goes for our friends Arturo and Parvati, too. Next thing we know, we’re all enrolled in the last hero school on Midgard (that’s hero speak for ‘Earth’). In fact, we’re the entire final freshman class.
“It’s not all bad. We get to go to school on an enchanted island. The girls get to ride flying horses, Arturo gets to go berserk, and I get to learn more about swordfighting than I ever wanted to know. We also get our own personal bard who sings our praises in deathless…well, verse that you wish would die, but it won’t.
“You’d think we’d also get to save the world. But as it turns out, there are about a million prophecies guaranteeing that Ragnarok is right around the corner and the world is literally toast, so all we get to do is die (heroically, of course).
“In the meantime, our mom winds up in Hel while trying to rescue our dad from, believe it or not, an even worse place. And for some reason even Odin won’t explain, we’re the only ones who can bring them back.
“Well, that takes care of summer vacation. I can’t wait for the school year to start!”