Six weeks after rebinding Fenris Wolf, Magnus meets Sam at the Thinking Cup on Newbury Street. She has been busy with school, Valkyrie missions, and flight school lessons funded by her fiance Amir Fadlan's family. Sam leaves to answer a Valkyrie call, and Magnus meets her informant Otis, one of Thor's goats, disguised in a trench coat and porkpie hat. Otis reveals he has a lead on Thor's missing hammer in a wight's barrow in Provincetown before an axe kills him from a nearby rooftop. Magnus chases the goat-killer across the rooftops of Back Bay.
Chapter 2: Your Standard Rooftop Chase Scene with Talking Swords and Ninjas
Magnus chases the helmeted goat-killer across rooftops, smashing a stained glass window at the Church of the Covenant along the way. Jack taunts and helps in the fight on the steeples. The attacker turns out to be a slim figure with green hair and mismatched eyes who shape-shifts between animals during the chase. After a brutal scrap that ends back near the Thinking Cup, the goat-killer escapes by leaping into Boston Public Garden.
Chapter 3: My Friends Protect Me by Telling Me Absolutely Nothing. Thanks, Friends
Back at the cafe, Magnus reunites with Sam, who is sporting a fresh black eye from her latest Valkyrie pickup. They examine the giant-forged iron axe Otis's killer left behind and worry that Loki is behind the missing hammer plot. Magnus returns to the Hotel Valhalla to find Blitz's shop closed and Hearth unreachable. His hallmates - T.J., Halfborn, and Mallory - are evasive about where the dwarf and elf have gone, which leaves Magnus rattled.
Magnus learns the new einherji Alex has been placed in the room across from his on floor nineteen, and that Alex is the goat-killer. Sam explains that Alex is a child of Loki, gender fluid (she/her today), and chose green-and-pink pottery as a way to fight back at the world. Magnus visits Alex's trashed suite, gets head-butted by her cheetah form, and comes away unsettled but intrigued by his new hallmate.
Chapter 5: My Sword Has a Better Social Life Than I Do
Back in his suite, Magnus studies the photos on his mantel and notices a snake-shaped mark of Loki has appeared on Randolph's face in a recent family photograph. He summons Jack, who confirms the symbol is one of Loki's brands. Magnus broods about the connection between Alex Fierro, his uncle, and Loki's plans, and worries about Annabeth, who has been silent since January.
Dragon Thursday means the floor nineteen crew - T.J., Halfborn, Mallory, and Magnus - head out to the courtyard battlefield to fight lindworms. A raven dumps the new recruit at their feet in the form of a brown-and-white weasel, who promptly transforms into Alex in a green hijab-free swirl of hair. Alex refuses a weapon, says she will improvise, and stalks into combat with the rest of the squad.
Chapter 7: Have You or Someone You Love Ever Suffered From Lindworms?
Wading into the battlefield with Alex watching his back, Magnus questions her about gender fluid identity and tries to find common ground from their shared time on the streets. The conversation is cut short when the lindworm Grimwolf corners them in the forest. As the dragon lunges at Magnus, his mind is yanked into a vision of Randolph's study, where Loki is waiting.
Chapter 8: I Am Saved From Certain Death By Being Killed
Paralysed between the battlefield and his uncle's study, Magnus inhabits Randolph's body while Loki brands his face and forces him to deliver a wedding invitation: in five days the giant Thrym will marry Sam as bride-price for Thor's hammer, or war will follow. Back in the courtyard, Alex garrottes Grimwolf from the dragon's neck while T.J. and Mallory shield Magnus. Magnus dies on the battlefield, decapitated by the thrashing lindworm.
Chapter 9: Never Take a Bubble Bath With a Decapitated God
Dead between battles, Magnus dreams. First he sees Randolph's yacht foundering in the storm that killed his cousins Caroline, Aubrey, and Emma. Then he surfaces as a disembodied head in a strawberry-scented bubble bath, where the severed head of Mimir consults him about Thor's missing hammer. Mimir confirms Loki is behind the theft, that the giant Thrym demands Sam as bride within five days, and warns that giant armies are massing on the borders of Midgard.
Hawaiian luau theme night in Valhalla's feast hall. Magnus sits with T.J., Mallory, and Halfborn while Alex and her Valkyrie sponsor Sam sit at the table of honour. Halfborn explains the Norse concept of argr - gender-fluid people - and Magnus starts to see Alex in a new light. Helgi the manager calls Alex up to be formally introduced before the einherjar can vote on whether she is worthy of Valhalla.
Chapter 11: What's a Guy Gotta Do to Get a Standing Ovation?
Helgi presents Alex as the newest einherji and the Valkyrie Vision screens roll Sam's body-cam footage. The video accidentally starts hours early, exposing Sam's mortifying breakfast conversation in which Abdel Fadlan tells Amir the engagement may be in trouble. The footage then cuts to Alex's actual death, defending a group of homeless kids from one of Loki's goons by shape-shifting into a cheetah and a host of other animals. The einherjar grudgingly cheer her in.
Chapter 12: Samirah and Magnus Sitting in a Tree, T-A-L-K-I-N-G
Magnus rides Jack into the rafters of the feast hall to catch Sam mid-flight and warn her about the goat-killer hiding in the branches of Laeradr. Sam alerts the Valkyries, then perches with Magnus while she explains what she glimpsed of Alex's soul during the death-pickup, including Alex's terror of being locked into one gender forever. They agree to fly to Provincetown in the morning to check the wight's barrow.
Chapter 13: Relax, It's Just a Little Death Prophecy
Magnus sleeps off twelve hours of post-Jack-Air exhaustion, then Sam saddles a winged horse and the pair fly to Cape Cod. They land at the Pilgrim Monument, the granite tower above Provincetown harbour where Sam believes the wight's barrow is hidden. Waiting at the door, to Magnus's enormous relief, are Blitz and Hearth, who have been holed up planning their assault on the tomb.
Chapter 14: Cry Me a Blood River. Wait. Actually, Don't
The four friends circle the base of the Pilgrim Monument until Blitz finds the trigger crack in the paving. Hearth sketches a rune that vaporises the slab, dropping the whole group into a pitch-black domed chamber. Magnus heals Hearth's broken ankle and his Frey-glow reveals twelve mummified draugr in wall niches, each clutching a corroded sword. There is no sign of Thor's hammer.
Chapter 15: All in Favour of Slaughterng Magnus, Please Say Aye
The lead draugr steps out of his sarcophagus and introduces himself as Gellir, prince of the Danes, owner of the legendary Skofnung Sword. Gellir is delighted to be freed and has no hammer to offer. When he learns Sam is a woman he refuses to unsheathe Skofnung in her presence, then announces that as the chief wight of the barrow he must still consume his rescuers. He rouses his twelve berserker bodyguards to attack.
Chapter 16: Hearthstone Unleashes His Inner Bovine
Magnus fights the draugr in close quarters while Jack insists on giving him a sword lesson. Sam torches zombies with her glowing spear, Blitz gets his fist stuck inside one's gut, and Hearth slams down the uruz rune of the ox, swelling into a bloodshot bovine wrecking ball. They cut down Gellir's twelve bodyguards until only the draugr king himself is left, sheltering against his coffin.
Chapter 17: Uncle Randolph Gets on My Naughty List BIG-TIME
As Magnus stands over the cornered Gellir, the back of the sarcophagus opens and Randolph steps out with Loki beside him. Loki freezes Sam mid-lunge by stopping her breath, brands Randolph's face afresh with his hand, and gloats about controlling his children's bodies through their blood. He drives Randolph to draw the Skofnung Sword and stab Magnus, but Randolph turns at the last instant and runs the blade through Blitz's gut instead.
Chapter 18: I Need to Learn Many, Many More Cusswords in Sign Language
Magnus cuts the Skofnung Sword and two of Randolph's fingers from his uncle's grip, then races to Blitz, whose wound from the cursed blade will not close without the Skofnung Stone. Loki explains that the stone lives with Hearth's estranged father Mr. Alderman in Alfheim, then demands the team retrieve it. Out of options, Hearth uses a rune to petrify Blitz into safe-to-transport granite, and the friends flee the barrow.
Chapter 19: Should I Be Nervous that the Pilot is Praying?
The petrified Blitz is bundled to Provincetown Airport, where Sam has begged her flight instructor Barry for an emergency charter. Amir Fadlan turns up at the airport, refusing to be left out after Sam's earlier confession, and joins the flight to Norwood Memorial in Barry's Cessna Citation. Magnus endures his first ever airplane ride while Jack pesters him with lovesick questions about the Skofnung Sword.
Chapter 20: In Case of Demonic Possession, Please Follow Illuminated Signs to the Nearest Exit
Mid-flight, copilot Barry is briefly possessed. The voice booming through him is not Loki but the goat-killer ninja from Boston, who orders Magnus to heal Blitz, seek out Heimdall, and bring Alex to Jotunheim if they want to defeat Loki's plan. Barry snaps back to himself with no memory of the message. Amir and Hearth are bewildered, Sam keeps the plane level, and the flight ends with Magnus, Hearth, and granite Blitzen parachuting toward Alfheim.