Adjudant-Chef Galoup, a dedicated member of the French Foreign Legion, spends his days reflecting on his past from the comfort of his home in Marseille. His mind drifts back to the vibrant yet challenging days spent in Djibouti, where he led a group of soldiers under the command of the charismatic Commandant Bruno Forestier. Galoup couldn’t help but both admire and envy Forestier's natural leadership and the strong bond he maintained with the men under his command, keeping a wristband bearing Forestier's name as a token of his admiration. Amidst the sun-soaked landscapes and the throbbing nightlife, he also had a Djiboutian girlfriend, and they shared joyful nights filled with dance.
The arrival of a new recruit named Gilles Sentain disrupts Galoup's reflections. Almost instantly, Galoup feels an irrational animosity towards Sentain, vowing to break the young soldier. This hostility reaches a boiling point when Sentain offers a canteen of precious water to a fellow soldier being punished under the sweltering sun. Galoup, in a fit of rage, knocks the water from Sentain’s hand, further escalating their conflict. In response to Sentain's defiance, Galoup takes him into the unforgiving desert and cruelly instructs him to find his way back to base alone. Unbeknownst to Sentain, Galoup has tampered with his compass, ensuring that the young man loses his way amidst the desolate landscape, ultimately leading to his near demise from dehydration in the barren salt flats.
As fate would have it, Sentain is discovered and rescued by local villagers, but he never returns to the legion, leading his comrades to believe he has deserted. The discovery of Sentain’s compass at a local market hammers home the misconception that he has perished, deepening the animosity against Galoup. With suspicions swirling that he may have harmed Sentain, Forestier makes the decisive choice to send Galoup back to France for a court martial, marking a somber end to his career within the Foreign Legion.
With a heart heavy with regret and uncertainty, Galoup meticulously makes his bed in the disciplined manner expected of a soldier. He stretches out atop it while clutching a pistol, reflecting on his choices as he reads aloud the words etched into his chest: > "Sers la bonne cause et meurs" ("Serve the good cause and die"). The film draws to a close with a poignant scene in a lively night club in Djibouti, where Galoup immerses himself in a vibrant performance, dancing acrobatically to the infectious rhythm of "The Rhythm of the Night," his personal tumult juxtaposed against the festive backdrop.
