The narrator documents the House in journals, fishes for food, and tends to the bones of fifteen dead people.

Ketterley, called the Other, meets the narrator twice weekly and renames him Piranesi while pursuing occult knowledge together.

Ketterley says the word "Batter-sea" to the narrator, who does not recognize it as a real London location.

The narrator slips in the flooded Drowned Halls while weakened by hunger and is caught by a reaching statue.

Ketterley threatens to stop their weekly meetings if the narrator abandons their shared search for arcane knowledge.

Ketterley warns the narrator that a new person called 16 is his enemy and speaking to her will cause madness.

An old man the narrator names the Prophet visits the labyrinth and discusses the dead, the statues, and Ketterley.

The narrator discovers that numbers in his older journals have been scratched out and altered, suggesting a hidden past.

The narrator retrieves torn scraps from gulls' nests in the Eighty-Eighth Hall and pieces together pages describing imprisonment.

Raphael arranges white pebbles on the floor spelling "Are you Matthew Rose Sorensen?" and a vague memory stirs in the narrator.

The narrator looks up Ketterley's name in his index and discovers Battersea is a London borough where Sorensen vanished.

The narrator reads the pieced-together journal account of how Sorensen was lured to Ketterley's home and abducted.

During the great flood, the narrator confronts Ketterley about his abduction and pulls Raphael to safety on higher statues.

Rising floodwaters crash Ketterley against the architecture of the labyrinth and kill him as he tries to board his boat.

After the flood, Raphael confirms the narrator is Matthew Rose Sorensen and he eventually chooses to return to London.

A man with no memory lives alone in a vast, flooded labyrinth, tending the bones of fifteen dead people and meeting weekly with the only other living person he knows, who calls him Piranesi. He is unaware that he was once a journalist named Matthew Rose Sorensen, abducted and imprisoned in the labyrinth by his supposed friend. Clues slowly accumulate — an unrecognized word, altered journal numbers, and a message spelled in pebbles asking if he is Matthew Rose Sorensen — until the full truth of his abduction crashes over him. A police officer named Raphael has entered the labyrinth to find him, while his captor Ketterley plans to kill her before she can succeed. A catastrophic convergence of tides becomes the turning point: the narrator confronts his captor, leads Raphael to the safety of higher statues, and watches the floodwaters kill Ketterley. Rescued at last, the narrator learns his true identity but never fully recovers the person he once was, and eventually chooses to return to London on his own terms.

The core arc of Piranesi's captivity, discovery, and return to the world.

The narrator explains his unique calendaring system, dating journal entries by observable events in the labyrinth rather than standard dates.

The narrator catalogs statues he loves, including the Faun and the Gorilla, and notes the Horned Giants unsettle him.

The narrator finds a leaf floating in the waters and wonders whether trees exist somewhere beyond the House.

Ketterley performs a ritual invoking a dead king called Addy Domarus; the narrator suggests using a star from a faraway hall.

The narrator stays overnight in the 192nd Western Hall to map stars and discovers a crowd of moonlit statues.

Walking home at dawn, the narrator finds 47 scraps of paper scattered across the Eighty-Eighth Western Hall floor.

The narrator writes a letter to Ketterley agreeing to help with the ritual despite his loss of faith in it.

The narrator finds an unsigned note in the First Vestibule asking for directions to a statue and writes a reply.

The narrator finds chalk writing left by Raphael on the pavement and writes a message back, signing it Piranesi.

Ketterley reveals he has bought a gun and insists that both he and the narrator must kill the Sixteenth Person.

The narrator blindfolds himself to partially erase Raphael's chalk message and adds a warning that Ketterley is carrying a gun.

Before the flood, the narrator moves the bones of all the dead up to a safe, high location in the House.

After the flood, the narrator finds Ketterley's body and tends to it as he does all the other dead.

The narrator guides Raphael on a tour of the halls; she tells him Arne-Sayles likely murdered all the dead.

Back in London, the narrator cuts his hair, relearns modern daily life, and decides to write the book Sorensen had planned.

This pool follows the quieter fabric of life in the labyrinth that shapes the narrator's world before and during his awakening. It traces his eccentric habits — inventing his own calendar, cataloging statues, finding a leaf and wondering about trees — as well as his gradual accumulation of clues that something is deeply wrong. He discovers scraps of mysterious writing, exchanges chalk messages with a hidden stranger, and makes careful preparations for a coming flood, all while slowly recognizing the danger surrounding him. Ketterley's acquisition of a gun and his insistence that the Sixteenth Person must be killed expose the threat the narrator has been blind to all along. The narrator's careful tending of the dead — before and after the flood — reflects his profound sense of duty to those who suffered in the labyrinth before him. The pool closes with his return to London, where he tries to rebuild a life from the fragments of an identity he can only read about in old journals.

The day-to-day discoveries and encounters that build and fill out the narrative.

The narrator lists all fifteen dead people he cares for and speculates that a Sixteenth Person might be reading his journals.

The narrator describes his journals and notes that his current notebook appears to be number ten, though earlier numbering is puzzling.

The narrator practices fortune-telling by observing which statues flocking birds land on and interprets their movements as coded omens.

The narrator presents Ketterley with star maps and announces he has lost faith in their quest for the Great and Secret Knowledge.

After Ketterley claims the narrator has forgotten previous episodes of doubt, the narrator resolves to re-read all his earlier journals.

After Ketterley threatens to kill him if he speaks to 16, the narrator privately considers breaking his promise and contacting her.

The narrator removes ornaments from his hair and practices hiding in preparation for the Sixteenth Person's arrival.

The narrator reads earlier journal entries about Sylvia D'Agostino, one of Arne-Sayles's followers who vanished after refusing his demands.

The narrator reads about James Ritter, who spent two years in the labyrinth and was later found imprisoned in Arne-Sayles's house.

The narrator detects a lemon perfume lingering in the halls and deduces that the Sixteenth Person has already passed through.

The narrator reads his earlier notes on Arne-Sayles's Theory of Other Worlds and discovers how the portal between worlds functions.

The narrator vomits and shakes after his journals prove that Ketterley abducted him and has been his enemy the entire time.

The narrator realizes Raphael is trying to save him rather than harm him and rewrites a flood warning Ketterley had erased.

Raphael plays a recording of her interview with Arne-Sayles and explains to the narrator how she learned to travel to the labyrinth.

The narrator takes James Ritter on a visit to the labyrinth and cautions Raphael against traveling there alone too frequently.

This pool focuses on the moments of realization and decision that transform the narrator's understanding of himself and his world. It begins with small puzzles — inconsistent journal numbers, birds behaving like omens, a vague reference to a possible Sixteenth Person — and builds through increasingly alarming discoveries in his own forgotten writing. Reading lost journals about Sylvia D'Agostino and James Ritter, the narrator slowly grasps that the labyrinth has trapped and destroyed people before him, by the hand of someone he trusted. When he finally pieces together his own history — learning Arne-Sayles's theory of portal worlds and confirming that Ketterley is his abductor — the shock is physical, and his emotional allegiances are completely reversed. He now sees Raphael as his rescuer rather than his enemy, and the story of his liberation becomes his own conscious choice rather than something imposed on him. The pool closes in the aftermath of rescue, with the narrator cautiously weaving between two worlds while maintaining his bond with the labyrinth he can never fully leave behind.

The key revelations and decisions that crack open the narrator's understanding of himself.