A pandemic of a new virus is raging in the world, but Stas does not wear a mask or wash his hands. Why are all these extra precautions needed if most people are asymptomatic? But his mother’s illness turns his ideas upside down: infection with the virus leads to complications and now, to save her, he needs an antibiotic, which, due to the pandemic, has completely disappeared from pharmacies, but not from Professor Chertoprud’s supplies. In the thirteenth room.