While visiting her ornithologist father in hospital, 13-year-old Isla meets Harry, the first boy to understand her and her love of the outdoors.
But Harry is ill, and as his health fails, Isla is determined to help him in the only way she knows how.
Together they watch a lone swan struggling to fly on the lake outside Harry's window. Isla believes that if she can help the damaged swan, somehow she can help Harry. And in doing so, she embarks upon a breathtakingly magical journey of her own.