In Curse Of Strahd, she appeared to the Pack as a Specter failing to nurse baby Walter, forever trapped as a ghostly servant. Though Zondra initially attacked the adventurers in rage and fear, she ultimately requested their help in saving her baby. They escaped the Death House after killing Walter; though she was destroyed in the resulting fire, the house's Curse remained.
A quiet but attentive girl, Zondra Zalenski was born poor in the Village of Barovia. As a young woman, she was employed by the Durst family as the head maid in their household. She was treated poorly by the matron of the Death House Elizabeth Durst, and was later involved in an illicit affair with Gustav Durst. The affair produced a baby, and thereafter she was primarily responsible for raising her son, Walter.
Zondra was eventually killed by her matron, stabbed to death and placed in a bloodied crate upstairs. Walter was taken downstairs, involved in a dark Curse to become the monster of the house.