In the Salt Mine

From the introduction:

The dark draug Mýsing had come up with a dastardly scheme to teach the margrave a lesson for interfering in his work. Through spies, Mýsing learned of Ljuba's travel plans and decided to kidnap her entourage. After the kidnapping, Mýsing and his draugar attempted to convince Ljuba to accept transfiguration into an undead, but she refused to yield. Ljuba then was kept alive as a prisoner in Mýsing's lair. The myrkdraugur no longer had personal contact with her, nor did any of his minions continue attempting to convince her to become a draugur. Instead, she was imprisoned but kept and fed well.