Geoffroy Lefayen, the narrator and protagonist of this slim book, is an outsider to others, even to himself: his mother was interned in a psychiatric hospital, and past the age of fifty he can count the few friends he has ever had on one hand. The Roger twins are among them, although they're either in prison or dead: we later learn that they were imprisoned for killing and embalming five people in a boat on the high seas, but although Geoffroy assisted (and passed with flying colours) in this operation, he was not seen to have any responsibility in the gruesome actions.
The sea is very much seen by Geoffroy as part of his life, and having worked before with Joël at the Pierres Noires lighthouse, he gets a job as lighthouse keeper of Cordouan, the isolated lighthouse to the west of Royan and Verdon. It is very obvious to any reader that Geoffroy is insane, although his main fear is of going mad. Who can stop the insanity?
Geoffroy prides himself in stuffing a conger eel, then feels compelled to kill and stuff two English tourists wishing to get married at the lighthouse, but how long can the insanity prevail? Joël's son is watching him through his ultra-powerful telescope, so Geoffroy's paranoia is based on reality. Does Lise, the insane engineer who eventually kills her (incestuous) husband and daughter really exist as a saviour to Geoffroy and his lighthouse/sea obsession, or is she, along with the wonderful sexual freedom she brings to Geoffroy, merely imaginary? We shall never know, as the heat is so much on Geoffroy's tail that everything has to blow.
The embalming process, and the tools used, are explained in a little detail. This is a disturbing book that would be a cult one if enough people were aware of its existence.