Unpleasant things are going on in an exclusive school for girls – things like murder… Late one night, two teachers investigate a mysterious flashing light in the sports pavilion, while the rest of the school sleeps. There, among the lacrosse sticks, they stumble upon the body of the unpopular games mistress – shot through the heart from point blank range. The school is thrown into chaos when the `cat strikes again. Unfortunately, schoolgirl Julia Upjohn knows too much. In particular, she knows that without Hercule Poirots help, she will be the next victim…