Herman Koch - Tisztelt M. úr!

The ever-celebrated writer M. achieved his greatest success with his novel about the mysterious disappearance of Jan Landzaat. The high school history teacher lost track of him after having an affair with his fabulous student, and was last seen at the vacation home where the girl and her new boyfriend spent the winter break. The novel became a bestseller and brought M. an international breakthrough, but now, at the end of his career, oblivion is increasingly his class.
Of course, this does not apply to his mysterious downstairs neighbor, who keeps an eye on M.. But what does it have to do with the infamous disappearance case?