Killdeer

She was looking for music. She found a mystery...
Elspeth Kolesar only meant to search the computer banks of her brother Anton's starship for new songs to relieve her boredom. What she finds instead are video recordings of a race called the Aelur, who, despite their feline faces, sing and laugh and speak just like her.
Reaching out in friendship to Nightsinger, a young man of the Aelur, Elspeth learns from him that Anton has kidnapped his clan of Fire Valley, taking them to a strange planet to study them. Worse, he means to do the same to their allied clan of Free Sky if he is not stopped.
Though she is Anton's ward, as much within his power as the Aelur, Elspeth vows to help, finding allies of her own in the clever queen of Free Sky, Duskdance, and her outworld husband, Suncrest. But when the time comes, Elspeth will have to face her brother alone.
Will the clash between Elspeth's two worlds destroy her, and strand all those she hopes to save? Or can she learn to balance herself between the future and the past, and fly free among the stars without forgetting the lessons she learned from a little bird called Killdeer?