Schooldays can be tough. Who will learn the fatal lesson? Late one night, two teachers investigate a mysterious flashing light while the rest of the school sleeps. In the sports pavilion, 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 Poirot's help, she will be the next victim...