In The Hallucinators, Pierre-Olivier Capéran begins with a deer viewed through binoculars, a grey hill, and a veterinarian holding his breath. A subtle distortion in reality is introduced, growing gradually as the story unfolds. The novel opens with a soldier in Abidjan waking up with unclear memories—recalling happiness before suddenly losing it. The tone is set through concrete details, altered perceptions, and an unnamed, looming threat. In the Morvan region of France, Martin Reinhard has recently taken over a veterinary practice in Château-Chinon. Tired, isolated, and still dealing with a recent separation, he notices a group of deer near his home. What seems like a peaceful scene takes a strange turn when Martin realizes something is wrong. A few words are enough to disrupt the calm: "The beech grove, the grass of the pasture and almost the entire right side of his field of vision had turned blue." From this strange stain, the narrative begins to spread its influence, altering the world around it. Capéran builds the story through a series of interconnected scenes, weaving together the Morvan, West Africa, the military, a gendarmerie investigation, a journalist, and events whose connections become clear only gradually. Each shift in perspective relaunches the reader's understanding of the story. The places are described with precision, and the gestures are detailed, giving weight to the strange elements. This attention to material detail keeps the story grounded in real-world settings, from houses and roads to offices and screens. The effectiveness of the novel lies mainly in its pacing. The chapters cut at the right moment, information is delivered in measured doses, and dialogues circulate a sense of unease. Capéran skillfully creates tension without losing the depth of Martin, a massive yet vulnerable character who remains rational even in fear. As he faces the strange symptoms, he searches, checks, and doubts. "His body was sending him a signal." The challenge is to determine whether this signal is truly his own. Despite its strengths, the novel occasionally falters. Over more than five hundred pages, some plot developments repeat patterns that have already been explored: the appearance of a clue, its verification, and a new lead. Some dialogues serve mainly to convey information, risking a functional tone for a time. When the action accelerates, the book sometimes prioritizes impact over suspense. These weaknesses are mostly felt in the transitions between scenes. However, The Hallucinators remains anchored by its direct, visual writing, which pays close attention to the details that unsettle. The reader moves forward like Martin, searching for the point where reality began to deform. Capéran does not rush the revelation; instead, he narrows the focus, brings the stain back into view, and shifts suspicions. A broad, tense thriller, its success lies less in the accumulation of dangers than in this persistent feeling: something in the image has been off since the beginning.