The Hollow (Hercule Poirot, #25)

Lady Angkatell, intrigued by the criminal mind, has invited Hercule Poirot to her estate for a weekend house party. The Belgian detective's arrival at the Hollow is met with an elaborate tableau staged for his amusement: a doctor lies in a puddle of red paint, his timid wife stands over his body with a gun while the other guests look suitably shocked. But this is no charade. The paint is blood and the corpse real!