On the eve of departure for the summer holiday with his wife Vera, Kristóf unexpectedly discovers black mold on the wall behind their closet. Overwhelmed with the situation and convinced it is caused by a water leak somewhere in the building, he begins knocking on his neighbours' doors in search of its origin. What seems like a simple maintenance issue soon spirals into a tragicomic housing revolution, forcing Kristóf to confront not only a crumbling apartment block but also the deeper cracks running through contemporary Hungarian society.