The following version of this book was used to create this study guide: Clarke, Susanna. Piranesi. New York: Bloomsbury, 2020.

The novel takes place in a mysterious, endless labyrinth. Its architecture is reminiscent of Ancient Greece. It has many rooms and hallways. The lower rooms contain sea-like waters that are subject to tides. The protagonist lives in the labyrinth and subsists on the fish and vegetation that it contains. He can see the sky in places, but he is unaware of any way to leave the labyrinth. The labyrinth also contains statues, as well as images carved or painted onto the walls. The skeletal remains of 13 humans are also in the labyrinth. The protagonist does not know who they used to be, but he preserves and honors the remains. The protagonist only ever sees one other person, whom he simply calls the Other. They meet and confer twice per week. The Other refers to the protagonist as Piranesi. The protagonist feels that that is not his name, but as he cannot recall his actual name, he accepts the name Piranesi.

Piranesi takes copious daily notes in his journals. The novel itself is presented solely via these journal entries. Piranesi is devoted to exploration, and he seeks to understand the labyrinth. The Other insists that the labyrinth contains the key to unlocking ancient, forgotten knowledge that will grant them immense power. Piranesi wishes to help the Other in this search. However, one day, Piranesi suddenly feels that they should cease this search. When he mentions this idea to the Other, the Other refutes the notion. Also, he says that Piranesi has suggested this idea multiple times before, and that the labyrinth seems to be affecting Piranesi’s memory. Piranesi finds that hard to believe, as he never forgets anything about the labyrinth itself. However, Piranesi does eventually realize that he cannot seem to remember anything prior to five years ago. Also, his journal entries only extend about five years back. Piranesi believes himself to be at least 30 years old.

One day, the Other says that someone else may be in the labyrinth. At Piranesi’s suggestion, they refer to the person as 16, since it would be the sixteenth person—following Piranesi, the Other, and the 13 sets of human remains—of whom Piranesi is aware. The Other says that 16 is dangerous and should be avoided, and even potentially killed. A few days later, Piranesi encounters an old man in the labyrinth. He says that he was sent by 16 to locate Piranesi and confirm his presence in the labyrinth. He also says that the Other’s real name is Ketterley. Later, Piranesi reads the earliest entries in his journals. He does not recall writing these entries, but they are in his handwriting. The entries contain references to many things that Piranesi does not recognize, such as ‘London.’ From these entries, he deduces that the old man is named Laurence Arne-Sayles, and that the Other—real name Ketterley—was a mentee of his. Arne-Sayles was a scholar who became a figure of controversy when he began insisting that he had discovered how to perform magic and travel to alternate planes of existence.

Piranesi eventually learns that his real name is Matthew Rose Sorensen, and that he was a scholar who was doing research for a book about Arne-Sayles. When he visited Ketterley to interview him for the book, Ketterley trapped him in the labyrinth, which exists in an alternate plane of existence. The labyrinth soon took Piranesi’s memories of his pre-labyrinth life. Piranesi realizes that the human remains in the labyrinth must be those of other people whom Ketterley trapped in the labyrinth as test subjects or forced research assistants. Piranesi also deduces that 16 must be someone who is trying to rescue Piranesi. Ketterley lures 16 to the labyrinth just before a foreseen flood, in an attempt to kill 16. Piranesi intervenes and saves 16, and Ketterley is killed in the flood. Piranesi converses with 16, who is a police detective named Sarah Raphael.

Raphael persuades Piranesi to return to the ‘real’ world. Piranesi’s pre-labyrinth memories do not return, but he is able to assimilate back into modern English society. He sometimes returns to the labyrinth, which he is able to do at will. He does not reveal the secret of the labyrinth to others. However, he feels that his time in the labyrinth has helped him to see beauty in unexpected places in the ‘real’ world.