The handsome school custodian did not have a chance to rejoice at his incredible luck for long: when he was returning home with a TV he had won in the lottery, he was attacked by unknown people and beaten so badly that the poor fellow found himself in a hospital bed. It would seem that this is a typical robbery, but the Detective Club, consisting of Holly, Tracy and Belinda, thinks differently. After all, robbers would hardly beat their victim, risking that he would drop and break a valuable burden. So the criminals needed something else, but what? Who could a harmless watchman stand in the way of? Day and night, the friends puzzle over this riddle, and then one day an unknown voice makes an appointment for them at dusk...