Final answer:
The subject of the question is a scene from a play or script involving Professor Plum, Yvette, and Mr. Green. It describes an incident where Professor Plum backs into Yvette, causing the chandelier to fall and pin Mr. Green beneath it.
Step-by-step explanation:
The subject of the question is a scene from a play or script. It is not clear which play or script the scene is from, but it appears to involve a character named Professor Plum, Yvette, and Mr. Green. The scene describes an incident where Professor Plum backs into Yvette, causing her gun to go off, which then makes the chandelier fall and pin Mr. Green beneath it.