Four long Hercule Poirot stories gather in a single volume, each running well beyond the length of Christie's usual short fiction while stopping short of a full novel. In the title case, Poirot and Chief Inspector Japp examine a woman found shot in a locked room on Guy Fawkes Night, the fireworks masking the fatal moment; the police read it as suicide, but the position of the wound and the wiped weapon point elsewhere. "The Incredible Theft" moves to a country house party where a self-made cabinet minister stages a gathering to flush out a spy, only for secret plans for a new fighter aircraft to vanish from a locked study. "Dead Man's Mirror" sends Poirot to the home of an autocratic baronet who summons him, then is discovered shot behind a bolted door with a shattered mirror nearby, every detail seemingly arguing for self-destruction. The closing piece, "Triangle at Rhodes," finds Poirot on a Mediterranean holiday watching two marriages and a magnetic newcomer drift toward a death he can sense before it arrives. The collection trades the breadth of the novels for tighter, puzzle-focused construction, with Poirot reading rooms, objects, and small inconsistencies rather than chasing wide casts of suspects. Two of the stories rework earlier, shorter Christie tales into fuller form, deepening character and setting while keeping the central trick. Each turns on the gap between an obvious surface explanation and the answer careful observation finally yields.