In a dimly lit library, Ms. Marple, an elderly detective, was celebrating her birthday party, feeling nostalgic for her younger years. She was seated among her close friends on a beautifully decorated table by the fire. Suddenly, the lights flickered, plunging the room into darkness, and a shot rang out. Before the partygoers could recover from the shock, they found a prominent author lying dead on the floor. A mustard stain on the author's shirt littered with bullet holes piqued their curiosity. They noticed that the window overlooking the courtyard was slightly open, but no one could be seen. While the guests discreetly headed to the nearby restroom, some were heard whispering about the possibility of a staged crime.