The events take place in a mysterious apartment building in St. Petersburg. The 4th floor of the building is always closed off because strange things happen there. The residents of the building are so afraid of the evil forces lurking in that place that they even broke the button for the 4th floor in the elevator. But one day, three young guys who wanted to "hype up" the local legend decided to unlock the mysterious floor and livestream their experience there. Their decision was reckless and led to horrifying consequences.