Katabasis

At Cambridge University, postgraduate magician Alice Law is desperate to recover the soul of her supervisor, Professor Jacob Grimes, after a fatal laboratory explosion. She believes her academic future depends on his favor and recommendation, but the circumstances of his death are more troubling than she admits. Alice failed to close a safety loop in the experimental pentagram and concealed her presence in the laboratory afterward. Fellow researcher Peter Murdoch also carries a secret: after Grimes appropriated Peter's research, Peter approved the experiment's protocols without properly checking them. Neither intended the professor's death, yet both believe their negligence contributed to it. Peter independently investigates entry into Hell and joins Alice's risky ritual. They pay half their remaining lifespans to descend into the Eight Courts, assuming that bringing Grimes back will repair their futures.

In the Fields of Asphodel, Alice and Peter discover that dead souls, called Shades, can remain in Hell rather than advance toward reincarnation. Four Cambridge students who died under Grimes's negligent supervision recall seeing him head deeper into the courts, while their own fear of losing privileged identities keeps them waiting. The pair climb a wall of bones, confronting Peter's fear of heights, and discover a landscape that shifts with perception. In Pride, a university-like library traps Shades in endless examinations and self-justification. Desire reveals prisoners of insatiable appetites. Along the river Lethe, whose water strips away memory, chalk-animated bone creatures begin pursuing the travelers. Ordinary chalk magic initially fails in Hell's strange soil. The hazards intensify Alice's already severe distress, caused in part by a permanent pentagram Grimes tattooed onto her arm during an abusive research experiment. It gave her extraordinary recall but left her unable to forget traumatic events. Peter's apparent unreliability, meanwhile, conceals the hospitalization and pain caused by his chronic Crohn's disease, which he has hidden to avoid pity and professional judgment.

A choice imposed by the Weaver Girl fractures their already damaged trust: although Peter chooses to continue their journey together, Alice, frightened that Peter intends to betray her, selects the option that would sacrifice him. A masked boatman rescues them from the goddess and the pursuing bone creatures. The boatman is Elspeth Bayes, a former Grimes student who died by suicide after suffering within the academic system. She reveals that the predatory bone constructs belong to the once-celebrated magicians Nicomachus and Magnolia Kripke and their young son Theophrastus. The family kills and experiments on travelers while seeking a True Contradiction, or Dialetheia, capable of unprecedented magic in Hell. Elspeth also shows that blood can sustain chalk spells in the underworld. Rather than trust their rescuer, Alice and Peter attempt to force Elspeth to reveal her research; she discovers the trap and expels them from her boat. Their betrayal demonstrates how deeply Grimes's competitive methods still shape their behavior.

The Kripkes capture Alice and Peter in an Escher-like geometric illusion. Facing possible annihilation, the two finally disclose their secrets. Grimes had made an unwanted sexual advance toward Alice, then retaliated against her professionally. Rather than rescue him out of devotion, Alice had planned to bind his soul to his exhumed remains and keep him as a captive subject of experiments. Peter admits that the exchange formula Alice found among his papers was intended to trade his own soul for Grimes's, not Alice's. He also explains his medical history and his negligent review of the laboratory protocols. They begin to recognize how Grimes exploited their insecurities and set them against each other. Peter devises a paradox that releases only Alice from the trap, using his own blood to activate it against her objections. Alice hears the Kripkes attack him and believes his soul has been destroyed, but she cannot directly verify his fate.

Alone, Alice moves through the lower courts, where the Furies question her broken promises and the city of Dis is crowded with Shades endlessly composing defenses of their misdeeds. A Shade calling himself John Gradus and a woman named Gertrude expose her to competing ways of enduring an apparently infinite afterlife. Gertrude's beautiful Rebel Citadel offers peaceful refuge but traps souls in static repetition. Escaping it, Alice realizes that imperfect, changing life remains worth pursuing. When another Kripke trap kills a wounded animal beside her, Alice uses its blood to break free, recovers her strength, and prepares to stop the family's attacks. With Gradus's guidance she ambushes the bone creatures, captures Magnolia and Theophrastus without killing them, and uses her own research to tether Nicomachus temporarily to an artificial corpse left in Cambridge. The agony the spell causes makes her recoil from her earlier revenge plan. Gradus intervenes when Nicomachus overpowers her, sending them into the Lethe. Nicomachus disappears into the river; Magnolia and Theophrastus voluntarily follow. Gradus later boards a vessel taking souls toward reincarnation. The Lethe begins dissolving Alice's permanent tattoo, relieving her unbearable memory while also erasing knowledge she desperately tries to preserve.

Elspeth finds Alice and brings her back aboard her boat. After they reconcile, Elspeth reveals that she had already discovered a genuine Dialetheia and that the Kripkes were hunting her for it. She gives the impossible, two-faced pomegranate blossom to Alice without demanding repayment. The flower can facilitate extraordinary magick only within Hell, and Elspeth believes it may be exchanged for a single boon from its ruler. The two cross the Lethe to an island beyond familiar geography. Elspeth, now willing to seek reincarnation for herself, remains aboard her boat while Alice approaches King Yama's throne.

King Yama summons Grimes for an audience without requiring Alice to surrender the Dialetheia. Grimes admits that he manipulated Alice's dreams to draw her to Hell, then proposes staying there indefinitely to exploit the flower's possibilities, indifferent to her survival or Peter's apparent death. Alice shows him the corpse-binding revenge spell she had devised but chooses not to perform it. Instead she casts Peter's organic-exchange spell, exchanging Grimes's soul for Peter's. Grimes disappears from the throne; the narrative does not establish where his soul goes. Peter emerges alive, and the two embrace, acknowledge their love, and begin to apologize for their past injuries. Alice then bargains with Yama for their return to the living world and a refund of their sacrificed lifespans. He grants passage home but restores only half of the years they originally surrendered. Together Alice and Peter climb back into the moonlit Fellow's Garden at Magdalene College. Their academic prospects remain uncertain, but they choose a shared future grounded in ordinary life and independent of Grimes's approval.