Twelve-year-old Callum McBride, home from school and bored in the holidays, discovers to his shock that he has an unknown talent: he can occupy the minds of animals and control their actions while leaving his body where he left it, seemingly lifeless. He's only just discovered this worrying ability when he meets Emma. Emma is a girl with her own issues and talents - including a computer-hacking talent that has previously previously resulted in a brush with MI6.
As the bond between them grows, Emma uncovers a surprising connection between Callum's powers and his adoption by a local family after he was found at less than a year old on the ferry that runs between Iona and Mull. Throwing themselves into an investigation into the link between Callum's strange abilities and his origins, they're soon caught up in a plot to steal a nuclear warhead. Only by thinking on their feet, trusting each other and using their abilities can they hope to stay alive and defeat the enemy they face together.