One suicide is a tragedy, but two suicides definitely require an investigation.
Jean-Louis St-Cyr and Hermann Kohler first met on the battlefields of France during World War I, when they served on opposite sides. Nearly a quarter-century later, during yet another international war, they meet again with some regularity to investigate unusual crimes (Tapestry, 2013, etc.). They're summoned to Alsace in 1943 to probe a pair of suicides at a German-run POW camp. One victim is Renée Ekkehard, the secretary of Col. Hans Rasche, the camp's commander; the other, whose corpse was found a week later, is a prisoner named Eugène Thomas. The detective duo receives a handful of lame excuses about official laxness in discovering and reporting the deaths of both victims, whose bodies have been placed in cheap coffins. Renée was believed to be visiting her family in Strasbourg; an anonymous letter pegs Eugène as an adulterer. Mindful of the nearby Karneval, abandoned since the Blitzkrieg but often rumored to be a spot for trysts and worse, locals speculate about an affair between the two suicides, but the detectives are skeptical. They're just as interested in the nearby Schrijen Works, a textile factory where Eugène labored and Renée was good friends with the owner's daughter. Within all these crosscurrents lies the truth that must be revealed.
The arch chemistry between the two competitive sleuths, the smattering of German and French, and the measured unfolding of the well-appointed plot all give St-Cyr and Kohler's 15th case a faint flavor of Poirot.