The Sisters in Isolation were an off-shoot religious branch of women who lived on Caladan's isolated Eastern Continent in a large Abbey. The Abbey provided shelter from the outside world, where the women, called sisters, would weave tapestries for sale throughout the Imperium, and meditate as they created. Many of the sisters who were members of the abbey had taken a vow of silence, and all who entered the compound pledged to never return to the outside world.
Near the end of the Corrino Empire, Lady Helena Atreides was sentenced to the Abbey, for her role in the death of Duke Paulus Atreides. Nine years later, Swain Goire was also sent to live with the Sisters for his role in the death of Duke Leto Atreides I's son, Victor Atreides, and the maiming of Prince Rhombur Vernius.
Thriteen years after the arrival of Goire, Duncan Idaho and Paul Atreides took refuge in the Abbey and with the Sisters, to escape the assassins of House Moritani, during the beginning of the War of Assassins of 10,187 AG. Though Helena granted them a few days of refuge, the hunters of Moritani eventually found the duo. They destroyed not only the Abbey, but killed Helena and Swain, and many of the Sisters in Isolation; although Duncan and Paul escaped.