Incident at School, or Our Finder Has Disappeared

In the life of sixth-grader Varya, amazing events have been happening lately. Her dad invents a finder robot that helps search for lost items and tidy up. But alas: Varya takes the finder to school, and there the robot disappears without a trace. Who could need it?
It is necessary to start an investigation. It will not only lead to unexpected results but will also help Varya make friends.