Sky Hawk by Gill Lewis
When Callum and his friends find Iona on Callum's farm they try to chase her back into the village. But Iona runs from them up into the hills. It is late and dark and snow lies in the mountain gullies. Worried for Iona's safety, Callum follows to find her shivering with cold but refusing to leave. She is guarding a secret hidden in the forest above the dark waters of the loch. So they make a deal. Iona shares the secret and in return Callum allows her back onto the farm. They form a deep bond of friendship and make a promise to keep their secret safe. It is a promise that will change Callum's world forever . . . She turned her head, and fixed me with her brilliant yellow eyes. She looked right into me. And suddenly I knew then, in that one moment, I was as much part of her world as she was of mine. Soar above the clouds in this enthralling tale of friendship, loyalty, and hope.