The Thief Knot

The Thief Knot, the fourth book in Kate Milford's Greenglass House series, is set in the fictional city of Nagspeake. Within Nagspeake lies the Liberty of Gammerbund, a walled, self-governing sanctuary district where people with complicated pasts live under asylum laws, beyond the easy reach of the city's police.

Marzana Hakelbarend, a socially anxious middle-schooler, lives in Gammerbund at the family home, Hedgelock Court, with her parents and their elderly housekeeper, Honora Catharping. Marzana's mother goes by Barbara Hakelbarend, but her real name is Violet Cross: She was once the captain of a legendary smuggling crew that faked its own death to escape capture. At home, however, she and Mr. Hakelbarend strictly enforce "deniability," telling Marzana almost nothing about her mother's past. Marzana treasures the few stories she pries from Honora, who secretly shares one tale from the old days each time Mrs. Hakelbarend returns a former crewmate's family letter without reply.

Marzana and her best friend, Nialla Giddis, are bored, convinced that nothing exciting happens in Gammerbund. When Emmett Syebuck, a customs agent the family met the previous winter at Greenglass House, arrives seeking help with a kidnapping case, the opportunity Marzana has craved appears. Emmett explains that Peony Hyde, the eleven-year-old daughter of mayoral front-runner Winston Hyde, was kidnapped after a welcome party near her school. The ransom demands one million dollars the Hydes cannot raise, and investigators suspect the crime may be a political attack on Hyde's campaign. Emmett asks to be put in touch with a mysterious figure called the Snakebird, an information broker whose existence Mrs. Hakelbarend deflects before promising to approach him herself.

Marzana asks perceptive questions, but her parents shut her out, citing the danger. She resolves to investigate on her own, focusing on the possibility the adults have dismissed: that Peony might be hidden inside the Liberty.

At Marymead Intermediate School, Marzana and Nialla notice their substitute math teacher, Mr. Otterwill, carries a bag from Peony's school and reveals he had a camp job there canceled that week. They recruit Emilia Cabot, a boarder at Marymead who knows the school's layout and can access its records. Nialla proposes adding J.J. Mowbry, a close-up magician skilled in misdirection, and his best friend Ciro del Olmo. Ciro's family has deep roots in Nagspeake's underground networks: His ancestors were camoufleurs, specialists in concealment, and his mother runs the Liberty's shadow cell phone network. A sixth member arrives when Milo Pine, Marzana's friend from Greenglass House, sends a gold reliquary vial and a figurine called a Sirin. These tools allow Milo's friend Meddy, a ghost bound to the inn, to travel freely. Meddy manifests on Marzana's doorstep and joins the team. Marzana names the group the Thief Knot, after a trap knot that resembles an ordinary reef knot but reveals tampering.

The investigation advances on multiple fronts. At Hedgelock Court, Marzana and Ciro eavesdrop through the fireplace on an interrogation of Rob Gandreider, one of the suspects. Rob swears on his Liberty warrant, an oath treated as binding within the sanctuary, that he is innocent: A prison guard released him on instructions from an unknown party, making Rob a planted red herring. The guard was blackmailed by a female caller whose knowledge likely came from a powerful carrier, or underworld information broker.

Emilia leads the group through a hidden dumbwaiter at school to access Mr. Otterwill's employee file, which reveals he was recommended by Victor Cormorant, an underworld information broker, and ran a comics club at Peony's school. Marzana looks up "snakebird" in a birding reference and learns the snakebird is often confused with a related species: the cormorant. This confirms her suspicion that Victor Cormorant is the Snakebird. Mr. Otterwill later reveals that his great-uncle Victor Cormorant arranged the position.

Ciro presents blueprints from his grandfather's archives showing stations for the Belowground Transit, a long-abandoned subway system beneath Nagspeake. One station, Cotgrave Wall, matches the layout of Marymead's Library, suggesting a hidden station lies beneath the school. Another, Ottomy Stalls, corresponds to an address in the Liberty. Nialla theorizes that Peony encoded a hidden message on the reverse sides of words she cut from a comic book for the ransom note.

Marzana, J.J., and Meddy travel to Whipping Hyde, a Nagspeake neighborhood, to check on Mrs. Agravin, the missing math teacher whose apartment turns out to be the Ottomy Stalls station. Meddy enters the locked apartment and finds a girl tied to a chair. Marzana calls emergency services, and after a confrontation with two pursuers, she cuts the girl free. Mrs. Hakelbarend arrives shortly after, having been surveilling the building on the Snakebird's tip. That night, Mrs. Hakelbarend deduces that the Snakebird was himself manipulated and suspects his granddaughter Tasha Cormorant, an aspiring carrier, is the true mastermind. Winston Hyde announces on television that he is withdrawing from the race, his face showing terror.

On Saturday, Marzana reveals a breakthrough: the rescued girl was not Peony. The impostor betrayed herself by misidentifying a character in Peony's favorite book series, and the binding rope used a knot she could have easily untied. Marzana connects the scheme to J.J.'s explanation of the shell game: the suspects, the substitute teacher, and Mrs. Agravin's absence were all misdirection. The real purpose was to force the Hydes from their home, which sits directly above Mergenthaler Street, the Belowground's central hub, now sealed by old iron, a form of underground metal contamination that blocks transit tunnels. A trustee portrait at Marymead identifies the impostor as Tasha Cormorant. Nialla and Ciro crack the ransom note by backlighting the assembled clippings, revealing Peony's message describing darkness, teacups, animal noises, and a smell like pool water.

The Knot splits. Nialla and Ciro go aboveground to relay the decoded message and find help, while Marzana, Emilia, J.J., and Meddy board a train operated by Brandon Levi, the Belowground's conductor, and ride through a maintenance tunnel to the sealed station. The concourse has been reshaped by old iron into a surreal landscape of hanging chairs and freestanding staircases. Two intruders cut through the ceiling from the Hyde house above: Moth and Christopher Fletchwood, sons of Tumbler Fletchwood, a deceased former crewmate of Marzana's mother. Moth had visited Hedgelock Court days earlier, seeking stories about their father, and Marzana now realizes Tumbler left his sons a treasure hunt ending at a locker in the station. When Moth seizes Marzana at knifepoint, J.J. and Meddy stage an illusion simulating Tumbler's ghost and planting a burning message: "You took a child / Where is she?" Moth's resolve shatters, and he drops the knife as Marzana's parents, Emmett, and police arrive.

Peony is found alive at an abandoned amusement park, in a tunnel with retired teacup ride cars surrounded by foxes and chemically treated water, her decoded message relayed to authorities by Nialla and Ciro. Tasha Cormorant escapes before she can be apprehended. Tumbler's real treasure turns out to be a poem distributed across sixteen lockers, a love letter declaring his sons his greatest treasures. In a separate locker, Emilia discovers two historic map kites, relics of Violet Cross's smuggling days. Mrs. Hakelbarend gives Marzana permission to share the story behind the kites with her friends, a significant break from the family's deniability. On the walk home, Mrs. Hakelbarend voluntarily begins telling Marzana a story from her smuggling days, marking a meaningful shift toward openness between mother and daughter.