That moment when you learn your friend is marrying a giant . . . eesh.
Magnus Chase hasn’t seen Samirah al-Abbas for weeks. When they meet, he’s taken aback by how tired she looks. He figures her exhaustion is from leading a double life as a Valkyrie and a mortal teenage girl. But he soon learns the truth. Sam’s father, the trickster Loki, has made a bargain with an earth giant named Thrym: Sam’s hand in marriage in exchange for Mjolnir, Thor’s mighty hammer, which Thrym has stolen.

Magnus isn’t going to let the marriage take place. But stopping it . . . that’s going to be a challenge. Mjolnir is the only thing keeping the giants from storming into Midgard, the realm of the humans. So far, the giants don’t know Thrym has the hammer. But if Sam doesn’t go through with the wedding, Thrym will spread the word that he has Thor’s weapon is in his possession. And then all Hel will break loose.
The solution seems simple. Find the hammer. Return it to Thor. Done.
Simple, except no one knows where the hammer is.

Meanwhile, back at Hotel Valhalla, a new einherji is making his mark. Or is it her mark? Magnus isn’t sure what to think of Alex Fierro, a gender-fluid child of Loki who shape-shifts with ease and wields a deadly garrote.

Alex has a role to play in Samirah’s upcoming nuptials and the retrieval of Thor’s hammer. But can Magnus and the others trust Loki’s child? And what, exactly, does Loki get out of the alliance forged by the wedding of his daughter Sam to the giant Thrym? Why would he help Thor get Mjolnir back? Magnus senses he’s missing a piece of the puzzle…and if he doesn’t figure out what it is, a missing hammer will be the least of their worries.