A crime has occurred in a closed school for girls! On a wonderful May day, during Sunday lunch, the headmistress and her brother fell dead. The seven pupils understand that Mrs Plackett and Mr Godding were poisoned, but who?! And if the neighbors find out about this, the school will probably be closed and the girls will be sent home. Meanwhile, one after another, very inopportune visitors arrive at the school (for example, an admiral in love with the headmistress!). So the girls decided to pretend that nothing had happened and hide the crime. In addition, it turned out that the headmistress’s financial affairs were very bad. So with what funds was the school maintained?! And who is the killer anyway? Each of the schoolgirls is talented in their own way, and by joining forces, they take on the investigation.