The novel starts in Cambridge and moves to the Republic of Venice, then to Dalmatia and the mountainous central Balkans. The monastery at Varna is a fictional place, not connected with the real town of Varna or Lake Varna in Bulgaria. In 1952 Trease wrote a prequel to "The Hills of Varna", The Crown of Violet. The title is taken from a quote from Pindar (see City of the Violet Crown). Set in ancient Athens, it is about how Alexis wrote "The Gadfly", a comedy defending Socrates, and contains vivid descriptions of the Greek theatre. As in "The Hills of Varna" and "Cue for Treason", the hero befriends a spirited, convention-defying girl who plays a vital role in the adventure (in this case Corinna, a metic). Its American title Web of Traitors refers to the subplot of a planned coup d'état against the Athenian democracy; a speech in Alexis's play is used to trick the plotters into revealing themselves. This could be a record, outside of science fiction and fantasy, for how far the events of a prequel have preceded the first novel.