Graduate student Kirill Vorobyov meets a stranger who asks him to carry an experimental device in his pocket - an emotional energy concentrator so that it can be charged with the energy of students during classes. Kirill becomes interested in the device and conducts a test in which he discovers that under certain conditions the concentrator shows scenes from the past. In one of these scenes, he sees an ancient castle and its inhabitants. At the same time, tenth grade schoolgirl Lilya Mikhailova disappears from the hall of the local museum. It turns out that before she disappeared, she was looking at the Becklow family ring in the window. Next to the ring lay a notebook with the legend of the ring written in it. The legend said that sometimes the ring begins to sparkle, and the person standing next to it disappears forever.