The Paris Natural History Museum stands at the intersection of scientific preservation and wartime possession. Its galleries hold an immense, carefully cataloged mineral collection, but the war makes the museum’s everyday instruments of custody—keys, crates, manifests, and safes—part of a struggle over who may move, hide, inspect, or claim its objects. Through the museum, the novel connects Daniel LeBlanc’s work as a locksmith to Reinhold von Rumpel’s search for the Sea of Flames and to the uncertainty surrounding the diamond’s identity and whereabouts.

Collections and wartime protection

As war approaches, the museum prepares to protect its collections by moving objects to country estates. Couriers carry things away, transport manifests are secured, and every crate is padlocked. The threatened holdings range from fossils and ancient manuscripts to jade, minerals, pearls, gold nuggets, and a sapphire described as large as a mouse. The scale and variety of the inventory matter: the museum safeguards objects for their historical and scientific significance, while the approaching conflict makes their physical location and custody increasingly consequential.

Daniel works late into the night as the museum’s principal locksmith. Among the objects he imagines might be at risk is the Sea of Flames, a 133-carat diamond whose presence in the collection is uncertain to him. The director has arranged for three decoys: one is to remain at the museum, while three stones—the real diamond and two other decoys—are sent in different directions, including one carried by Daniel in his tool case in a field west of Versailles. The carriers are not told which stone is genuine; each is expected to behave as though it is. Daniel tells himself that his cannot be the real diamond, but its appearance and value leave him unable to dismiss the possibility.

Galleries, records, and restricted rooms

The Gallery of Mineralogy displays what remains after other objects have been removed. Von Rumpel walks among empty cases whose felted shelves retain the outlines of missing specimens, as well as minerals still on display: yellow topaz crystals, pink beryl, and tourmaline from Madagascar. The scene sets visible fragments against the larger collection that has been taken elsewhere. It also shows the museum as an ordered institution: its holdings are registered in extensive folios, and Professor Hublin explains that the catalog already contained two hundred thousand entries by 1850.

The museum’s account of value differs from von Rumpel’s. Hublin describes a collection that began under Louis XIII as a Cabinet of Medicines and grew into a record of minerals from around the world. The curatorial principle is to collect the different kinds of minerals, not to rank one above another. Von Rumpel, however, is not satisfied with a public tour. He asks specifically for specimens that are not on display and for an object recently brought out of the vaults. The museum’s commitment to safeguarding its holdings thus meets an occupying officer’s demand to see what has been kept from public view.

Access to the hidden collections is controlled by a chain of doors and custodians. A small locked door at the back of the main gallery requires two keys. Beyond it, the visitors descend a winding stone staircase, pass a second gate, and enter a storeroom of dropcloths, pallets, and crates. Behind a sheet of plywood is a combination safe; inside it is another, heavier box, which the assistant director and Hublin must lift together. The route makes security tangible, but it also reveals its limits: access depends on keys, staff, and the cooperation of people who know how the rooms are arranged.

The diamond and uncertain provenance

The diamond’s story is deliberately entangled with reproductions. In the two months before the invasion of France, Dupont makes three replicas for the museum, using a casting rather than the actual diamond; he never sees the original. Von Rumpel believes him. The three replicas and the real stone therefore form a group of four, with one stone locked in the museum basement and the other three dispersed. Neither the visual promise of the diamond nor the act of cataloging and securing it can by itself settle which specimen is genuine.

That uncertainty gives the museum’s arrangements a double purpose. Dispersal may protect the original by making the carriers—and anyone pursuing them—unable to distinguish it from the copies. But the same plan creates a broken chain of knowledge: the director, the carriers, and later investigators do not share certainty about the identity of each stone. Von Rumpel’s pursuit turns that gap into an opportunity for obsession. He remembers a pear-shaped diamond that he believed was the Sea of Flames, and its blue interior becomes inseparable in his mind from the legend that its keeper will live forever. His conviction grows from an encounter with a stone, but the museum’s copying and dispersal make conviction different from proof.

Keys, letters, and the search for Daniel

The museum’s reach persists after Daniel is separated from his family. French policemen arrive at the LeBlanc household at the request of the Paris museum and explain that Daniel has been convicted of theft and conspiracy. They say that the museum has written to wardens and prison directors throughout Germany, although they do not know which prison holds him and think it could be Breitenau. Their questions turn to the two letters he has managed to smuggle out, to his keys, and to the belongings he brought with him. Marie-Laure LeBlanc remembers that Daniel returned his museum keys before leaving and that he took his rucksack when the director summoned him back.

A letter from Daniel gives the museum’s former locksmith a different relation to keys. He recalls having carried them throughout his life; in captivity, he hears them in the mornings when people come for the prisoners and finds his own pocket empty. He says that he dreams of the museum. The institution is no longer simply his workplace or a guarded storehouse: it persists in his memory alongside the practical knowledge and identity attached to his trade. His clue to Marie-Laure points her toward Etienne’s house, connecting his absence to an object or secret hidden beyond the museum itself.

Narrative significance

The museum’s significance lies not only in the treasures it houses but in the systems that make them visible, movable, or inaccessible. Catalogs record specimens, keys grant entry, replicas frustrate identification, and wartime correspondence follows a prisoner across borders. These mechanisms place the diamond’s legendary aura beside concrete questions of custody and provenance: what is the original, who knows where it is, and who has the authority to claim it? The museum’s orderly practices offer protection, yet the war exposes how easily preservation can become entangled with secrecy, coercion, and pursuit.