Ben, a ten-year-old Irish boy, discovers his mute sister Saoirse, whom he blames for the apparent death of his mother, is a selkie who has to free faerie creatures from the Celtic goddess Macha.
"Saoirse is a child who is the last of the selkies, women in Irish and Scottish legends who transform from seals into people. She escapes from her grandmother's home to journey to the sea and free fairy creatures trapped in the modern world"--from www.imdb.com.