Le Mystère des XV is a French novel by Jean de La Hire, initially published in serialized form in 1911 in the daily newspaper Le Matin. It was later released in book format in 1922 by in two volumes titled Le Mystère des XV and Le Triomphe de l’amour. A subsequent edition appeared in 1954 by Éditions Jaeger under the titles Le Secret des XII and Les Conquérants de Mars. Despite the delayed French reissues, the novel was translated into other languages during the first half of the 20th century for publication abroad.
The novel is a sequel to Jean de La Hire’s earlier serialized work ("The Man Who Can Live in Water"), set 25 years later. It introduces the character Léo Sainte-Claire, known as the Nyctalope, and recounts his first adventure. The plot centers on a secret organization called the XV, which abducts fifteen young women in Paris with the intention of transporting them to Mars, a planet it seeks to conquer. The Nyctalope, whose fiancée is among the abductees, pursues the organization, first traveling to the Congo and then to Mars. There, he confronts the organization before becoming involved in a broader conflict with the Martians.
This adventure novel is part of the tradition of European scientific romances from the late 19th and early 20th centuries that take place on Mars. While it includes references to The War of the Worlds by H. G. Wells, Le Mystère des XV introduces several innovations. It is considered the first French novel to depict the colonization of Mars by Earth inhabitants. Additionally, Jean de La Hire presents one of the earliest examples of a superhero in popular literature by attributing the ability of nyctalopia to his protagonist.
Presentation
The novel consists of four parts separated by interludes.
Sainte-Claire the Nyctalope In Le Mystère des XV, Xavière de Ciserat is abducted by Koynos, leader of the secret organization the XV, after spending an evening with her fiancé, Léo Sainte-Claire. She is taken via radioplane to Mars, where Koynos expresses his affection and desire for her to join him in conquering the planet.
On Mars, Xavière learns that other young women, including her sister Yvonne, have also been abducted. Koynos operates under Oxus, who previously threatened Earth with the HictanerThese events are recounted in Jean de La Hire’s novel L’Homme qui peut vivre dans l’eau, published in the newspaper Le Matin between July and September 1909. twenty-five years earlier and now orders Koynos to return to Earth for a final mission.
In Le Mystère des XV, Léo Saint-Claire, known as the Nyctalope, investigates the abduction of his fiancée, Xavière de Ciserat, and identifies the kidnappers’ base in the Congo. He organizes an expedition with Louis de Ciserat, the Minister of the Navy, and five companions. During their airship journey to Africa, Koynos, a member of the XV, confronts Léo and throws him overboard.
Léo survives by using his coat as a parachute and is rescued by an English ship, which takes him to Spain. There, he learns that English inventor Klepton is hiding on Ibiza. Léo meets astronomer Camille Flammarion, seeking his aid for a journey to Mars, and travels to Ibiza to acquire an aircraft, the Condor, from Klepton, who joins as captain.
In Le Mystère des XV, Léo Saint-Claire, the Nyctalope, gathers his expedition team in Brazzaville and approaches the XV’s terrestrial base aboard the Condor. He receives a message revealing that his sister, Christiane, is being held in France. Suspecting betrayal, Léo interrogates Camille Flammarion, who is exposed as Thoth, an XV agent, and executed. Léo then infiltrates the base with Maximilien Jolivet, whose sister is among the captives on Mars.
Through the worlds After an extended journey through the jungle, Léo Sainte-Claire and Maximilien Jolivet reach the radiotelegraph station. While Sainte-Claire searches for a way to enter, Jolivet is captured and tortured by the station's two guards. After three days of unsuccessful attempts to locate an entrance, Sainte-Claire gains access following Jolivet’s escape and neutralizes the guards.
Meanwhile, after a seven-day interplanetary journey, Koynos arrives on Mars ahead of Oxus. Summoned by the leader of the XV, Alkeus is assigned to prepare for the anticipated arrival of the Nyctalope. Distraught over his unrequited affection for Yvonne de Ciserat, Alkeus announces his intention to sacrifice himself by ramming his radioplane into Sainte-Claire’s. Displeased with Koynos's failure to eliminate Sainte-Claire and destroy the African base, Oxus instructs him to sacrifice himself as well if the first collision fails. Despite these orders, Koynos pledges to Xavière that he will spare Léo’s life.
Meanwhile on Earth, Léo Sainte-Claire interrogates the guards, Normand and Breton, to prevent the destruction of the station. Gaining insight into the operations of the XV organization, he organizes a mission to Mars with a group of fourteen individuals to rescue the captives. A secondary objective is to facilitate a potential French military intervention on the planet.
On Mars, Alkeus identifies five incoming radioplanes and carries out his suicide attack, successfully destroying one.
On Mars Léo Sainte-Claire learns that Alkeus’s suicide attack destroyed the aircraft piloted by Admiral de Ciserat. Shortly thereafter, another vessel approaches, piloted by Koynos, who warns him not to land on Argyre Island, where Oxus has concentrated his forces. The Nyctalope’s expedition instead lands on Niliaque Island, where the eleven survivors begin their exploration.
In Cosmopolis, Oxus observes that all his agents, except Kipper—who is guarding Félicie Jolivet—have fallen under the influence of the captives. Koynos returns and informs Oxus that Alkeus destroyed one of the Earth ships, but withholds information about the arrival of the remaining four.
Warned by a servant of Koynos about potential dangers, Léo Sainte-Claire decides to infiltrate Cosmopolis to meet with Koynos. Meanwhile, Koynos returns to Xavière de Ciserat and makes a declaration of affection, which elicits a strong emotional reaction from her sister, Yvonne. Overwhelmed by her feelings, Yvonne leads Koynos to her room.
Upon arriving in Cosmopolis, Léo meets Koynos, who escorts him to Xavière. As Léo reunites with his fiancée, Oxus enters with his guards and orders the arrest of both men. They are brought before the tribunal of the XV, which, suspecting Koynos of betrayal and identifying Léo as a threat, sentences both to death.
The Nyctalope against the XV
After being sentenced to death by the tribunal, Koynos is executed by beheading, while Léo Sainte-Claire is imprisoned awaiting execution. That night, Xavière de Ciserat enters the dungeon and frees him. Sainte-Claire then proceeds to the residence of Oxus, where he uses his nyctalopic vision to overcome the guards and apprehend the leader of the XV. He informs Oxus of his plan to imprison him in secret for a month before reinstating him at the head of the organization. While in Oxus’s office, Léo examines the XV's plans and, impersonating Oxus, uses the telephone to instruct Kipper to begin the conquest of Mars.
As the members of the XV depart Cosmopolis under Kipper’s command, Léo Sainte-Claire uses the opportunity to reunite with his companions on Niliaque Island and bring them back to the city. Disguised in the white uniforms and green boots of the XV, the group presents itself to the inhabitants as the new governing body. Sainte-Claire publicly announces that, in the absence of the original XV—who have left to confront the Martians—eleven new members have been appointed to administer Cosmopolis, with himself assuming leadership under the name Oxus II.
Kipper’s son, Abbou, recognizes Sainte-Claire and, after capturing Xavière, informs his father of the deception. Kipper returns with his forces and demands control of the city in exchange for Xavière. Sainte-Claire refuses and insists on Kipper’s surrender. Kipper then realizes that his son has been misled and that the body believed to be Xavière is that of Abbou’s mother. Enraged, Kipper kills his son and subsequently crashes his hydroplane. Following these events, the remaining members of the XV submit to Sainte-Claire.
Three weeks after the establishment of control over Cosmopolis, approximately 3,000 French soldiers arrive on Mars, having been invited by the Nyctalope. Among them are the astronomer Camille Flammarion, serving as a scientific advisor, and Christiane, the adoptive sister of Léo Sainte-Claire. He reveals to her that she is the daughter of the Hictaner and Moïsette, and thus the granddaughter of Oxus. A council is convened, composed of the former members of the XV, Sainte-Claire’s companions, and the French military command. This body forms the new Earth-based military government on Mars. Oxus is appointed president of the council, and Sainte-Claire is named commander-in-chief.
Léo de Sainte-Claire and Xavière de Ciserat are married following their reunion. Under the Nyctalope’s command, the Earth expeditionary force departs from Argyre Island to engage the Martians. Confronted by a new weapon that impedes the advance of the Earth ships, Sainte-Claire undertakes a solo mission to capture a Martian for intelligence purposes. He successfully seizes control of a Martian tripod, infiltrates the enemy camp, and captures two Martians before returning to base.
Epilogue After partially deciphering the Martian language, the Nyctalope sends one of the captured Martians back to negotiate with his people. A peace agreement is subsequently established with the three major Martian nations. Later, when conflict arises between two of these nations, the Earth delegation, under the leadership of the Nyctalope, plays a decisive role in the outcome.
Characters
The Nyctalope
Léo Sainte-Claire, a French explorer known for his night vision, is referred to by the nickname "the Nyctalope." He is portrayed as a bold adventurer and is the son of Jean Sainte-Clair, the protagonist of Jean de La Hire's earlier novel L’Homme qui peut vivre dans l’eau, published in 1909 in Le Matin.
Le Mystère des XV is the first adventure of Léo as recounted by Jean de La Hire, in which he sets off in pursuit of the organization known as the XV, responsible for kidnapping his fiancée, Xavière de Ciserat. Alongside his companions, he takes control of the XV station in the Congo, then travels to Mars to wage direct battle against the XV. Endowed with extraordinary willpower, he overcomes all obstacles through audacity and the psychological dominance he exerts over his adversaries.
After the defeat of the XV, the Nyctalope marries Xavière according to Martian customs.
Allies of the Nyctalope The novel recounts the Nyctalope’s efforts to rescue his fiancée, Xavière de Ciserat, who has been abducted by the XV organization. Their leader, Oxus, orchestrates the kidnapping of fifteen young women—including Xavière, her sister Yvonne de Ciserat, and Félicie Jolivet—with the aim of making them wives for the leaders of a colony on Mars. However, the presence of these women disrupts Oxus’s plans due to the influence they exert over their captors. Xavière undermines Koynos’s loyalty, while Yvonne's actions contribute to Alkeus’s suicide. Yvonne, in turn, loses her sanity after learning of Koynos’s death. The XV organization engages in systematic abductions. Christiane Sainte-Claire, the Nyctalope’s adoptive sister, is also kidnapped in an attempt to manipulate him. Her origins are revealed at the end of the novel, when the Nyctalope informs Oxus that Christiane, newly arrived on Mars, is his granddaughter, the child of the Hictaner.