This thriller, set in Old Downtown Belgrade during the 1990s, focuses around adventurer and gambler Pop, nicknamed after his late father who was a priest. After twenty years of life abroad he decides to break with his past and return to his home town, where he is warmly welcomed by his brother, the famous architect and his old friend Laki. Pop is tormented by the guilt over the death of his young mate whom he did not help when he could have and soon becomes an object of romantic struggle between a mysterious mother and her daughter. All of a sudden he finds himself in the midst of a mystery evolving around the ancient Arian sect that shook the foundations of Christianity during the III century AD. The sect used to have a stronghold near Belgrade, but apparently its secrets still haunt the town as the sect left indelible marks on the destinies of past and present generations. The action leads Pop to the unknown dungeons of Kalemegdan Fortress where, with the help of his brother, he finds out about the daughter he never thought he had.