The magazine had found him a hotel near Notre Dame de Lorette, north of the Bourse, in the foothills of Pigalle. The room had floral wallpaper that was coming unstuck near the cornice. It smelled like most of the cheap hotels his life as a reporter had sent him to, of failed plumbing and cigars. The window overlooked a courtyard where some cab horses whickered and stamped on the cobbles.

From a stand on the rue des Martyrs, Anton bought an armful of newspapers and flicked through them to see if Monsieur Poincaré had yet returned from Moscow – and if so what alliance with the Russians he had built to go with his undertakings to the British. But he found little about the looming war; almost all the space was given over to Henriette Caillaux’s state of mind and to the details of how her relationship with her husband, the imposing Joseph, minister of finance, had begun when both were married to other people.

The court of assizes met in the Palais de Justice on the Île de la Cîté. The courtroom held around 300 men, including the press, which made a peculiarity of the female defendant, whose mauve blouse was almost the only flash of colour among the black morning coats and legal gowns. It was a cavernous room, in which many oak trees had gone to benches and to panels that reached up to the ceiling, from which hung glass-globed chandeliers. Anton’s seat was in a back row, among the other reporters, and he had to fight for a place between two Italians.

Henriette Caillaux, under questioning, described herself as ‘bourgeoise’, and, apart from a fancy feather in the band of her hat, there was little to suggest otherwise. With her narrow mouth and slightly hooked nose, she looked more like a housekeeper than a femme fatale. Her victim’s paper, Le Figaro, described her as having the ‘banality of a shop girl’. Most of the Paris press thought Caillaux had been about to drop her, as suddenly as he had left his first wife, and that her desperate act had been her way of forestalling him. If she was found not guilty, she would be shackled to a marriage in which love had died. One columnist declared she would be better off going to the guillotine.

Looking at her impassive face and sober clothes, Anton wondered what control she had once wielded over Caillaux, himself a known womaniser. Why had he forsaken his first wife, Berthe, a society beauty, for this woman with the pursed lips? Henriette had carried the pistol, a Browning automatic, hidden inside a large fur muff; but what other powers, fatal not to Calmette but to her husband Joseph, had she concealed beneath her clothes?

The inner lives of others were unknowable; and in that mystery lay the interesting part of the drama. The complexity of what they must have felt was at odds with the vulgar entertainment of which they had become the cast, Anton thought. The newspapers’ language of scandal and outrage could barely hint at the murkiness of the desires experienced by the participants in their stuffy apartments.