Buhez Sante Barba ("The Life of Saint Barbara") is a mystery play in Middle Breton verse on the life and miracles of the martyr Saint Barbara, daughter of King Dioscurus of Nicomedia.
Barbara, who has secretly embraced the Christian faith, is carefully guarded by her pagan father, who keeps her shut up in a tower in order to preserve her from the outside world.
When her father finally learns that the three windows are intended to symbolise the Holy Trinity, he realises that Barbara has denounced the old gods and converted to Christianity.
Dioscurus is furious and decides to kill her, but God transports her to the mountains, where she meets two shepherds, Gueguen and Rivallen.
Dioscurus sends her to his torturers, who do not shrink back from employing a variety of techniques to inflict pain and suffering, including the use of fire, knives and hammers.