In the 12th century AD, Venice is little more than an agglomeration of small islands: the magnificent city is yet to be born. Here, in this northern backwater, a group of artisans have proven themselves to be unrivalled in an art form that produces works of such astounding beauty that many consider it mystical in nature and think its practitioners possessed of otherworldly gifts: glassmaking. Presciently aware of the power they wield and the role they will play in the Venice of the future, the Venetian glassmakers inhabit a world of esoteric practices and secret knowledge that they protect at all costs. Into this world steps Edgardo D'Arduino, a cleric and a professional copyist. Edgardo's eyesight has begun to waver - a curse for a man who makes his living copying sacred texts. But he has heard stories, perhaps legends, that in Venice, city of glassmakers, there exists a stone, the 'lapides ad legendum,' that can restore one's sight. H