Magnus Chase, a 14 yr old boy, has never met his dad, and his mom had recently died from a tragic fire.
2 years later, Magnus is by himself on the streets with his only friends Blitz and Hearth.
Magnus' cousin and uncle come to Boston, the city where Magnus lives, looking for Magnus and putting up signs saying "Missing 16 yr old Magnus Chase,"
Magnus tries to find out what his uncle wants, so he follows him around. After a few minutes, Annabelle, Magnus' cousin, says '' Where is Magnus? I want to strangle him". Also Magnus finds out his Uncle Randolph is involved. Uncle Randolph is hated throughout the Chase Family for not sharing his huge inheritage from Magnus' grandparents
Magnus sneaks into Randolph's house to find out why his relatives need to see him. After a while in the house, Magnus finds nothing, but Randolph comes back to find Magnus trespassing. Randolph, a former history teacher, starts telling Magnus things like your dad is a Norse god, and then Randolph takes Magnus to a random bridge.
Magnus is told to summon a sword with only his hand by his Uncle, but Magnus thinks he's crazy and tries with minimal effort. Once a fire giant from hellheim (The Underworld) appears , Magnus realizes that Randolph isn't crazy, and tries with full effort. He finally pulls the sword out of the river and has a massive fight with Surt, the fire giant, ending with magnus drowning.