Semyon Barinov is an engineer at a research laboratory. That day everything seemed to be as usual. It was five o'clock in the morning. But at some point, the corridors of the research center were filled with thick purple smoke. After some time, Semyon woke up, and everything in the center became somehow different. True, only Semyon sees this. For other colleagues, nothing has changed. Will Semyon be able to unravel the mystery of what happened on that ill-fated day? Are his colleagues really friends or are they hostile aliens? And who is this girl with a beautiful voice who was not in their laboratory before?