Sister Drab was a veteran shryke sister who, along with Matron Featherhorn, organized an attack on the Undertowners fleeing to the Free Glades, intending to sell them and reestablish the Great Shryke Slave Market. After torturing a librarian knight for the location of the Undertowners, Sister Drab and Matron Featherhorn sent Mother Muleclaw the Third and the new shryke sisterhood to attack. Sister Drab's plan failed when Mother Muleclaw was killed and the shryke army was destroyed.