Exploring thoroughly modern taboos

In 17th-century Tuscany, a church play is performed for the benefit of young aristocrat Cosimo. In the play, a grotesque old woman gives birth to a beautiful baby boy. The child's older sister is quick to exploit the situation, selling blessings from the baby, and even claiming she's the true mother by virgin birth. However, when she attempts to seduce the bishop's son, the Church exacts a terrible revenge.