Bostjan Dvorak moves through Berlin like a hunter without a gun. In forgotten corners of U-Bahn stations, in dusty ventilation grids, he seeks out hidden butterfly caterpillars. But he is not your traditional butterfly collector. After helping them breed in his small apartment, this passionate amateur entomologist releases them back into the big city sky.

Some of Bostjan's favourite butterflies embark every year on a migration to Africa that is becoming increasingly uncertain. His own life seems no less precarious than theirs in the present time. However, his family has also always lived so, in a history stretching back to the international intrigues of Cold War Europe. We travel with Bostjan to his hometown Piran, where he found his first rare specimens as a child. These days he tends to spot caterpillars on the edges of motorways and airport landing strips. A far cry from what we imagine to be "nature".