Twelve years ago, in a village on the edge of a pine forest not far from Lithuania's elegant capital Vilnius, workmen constructed an unusual warehouse. It was the size of an Olympic swimming pool with no windows, many air vents and no stated purpose. The site had formerly been a riding stables and a paddock. It had also served as a local watering hole — a welcome one since the village lacked a bar or restaurant. The new building was shiny and modern, incongruous amid the tumbledown farm buildings and Soviet-era housing blocks. The convivial atmosphere of the riding club was replaced, in the words of one local inhabitant, by "this certain emptiness".

Naturally, the neighbours were curious. They speculated about the new building's function. Was it a military listening post? A drug factory?