Wolf wing - Tanith Lee

Free at last, Claidi and Argul are married in a brilliant ceremony, and look forward to their life together. But, nagged by her past, Claidi decides they must return to her birthplace, the House, and rescue her fellow slaves.

On arrival they discover that a revolution has taken place, sparked by Claidi's escape. A benign regime is now in charge, headed by the valiant Dengwi. However, during a grand dinner, Dengwi - to her own astonishment - is revealed to be the daughter of a former prince. She departs with Claidi and Argul, summoned by Ironel Novendot of the Wolf Tower.

Once with Ironel, the trio are joined by Winter Raven, Venn and Ngarbo. Then Ironel breaks her news: Ustareth, mother of Argul and Venn is alive, and has invited the young people to her new land, Summer. The party, unable to refuse, knows that at the end of their journey waits a woman, the science-sorceress, who has perhaps manipulated each of them since the day they were born ...

Not only Claidi is asking - what is the answer to the riddle of Ustareth?