Ioanna met the Fifth Doctor and Nyssa Traken on the last day of the 12th century. She told them that the local villagers wouldn't let her people attend the church services on the midnight of the century. According to belief, at that time the dead would appear to those in the church, allowing them a last time to see their loved ones.
Ioanna and Nyssa sneaked into the church during the service, and Ioanna saw a "ghost" of her mother. However, when the Doctor entered the church, countless alien "ghosts" appeared, and Ioanna turned against the Doctor and Nyssa, calling out for the villagers to stop them. The villagers set the church on fire, and Ioanna and the villagers died in the fire. (PROSE: The Church of Saint Sebastian)