From his very first day at Flintworne Junior School, it is apparent that there is something different about Leon Sparks. Quite how different is known initially by a very few - the headmaster, Mr Knutt; Leon's Year 5 teacher, Mrs Gulliver; the school's caretaker, Mr Flynn; and two unconventional 'school inspectors', who keep him in sight at all times. Soon, the true nature of the unassuming, pale-skinned boy who clutches a silver briefcase, is revealed to a handful of new school friends, and is suspected by another of the school's teachers. But when reports of strange lights over the school appear in the newspapers, shadowy agents from a foreign land also begin to show a keen interest in the school and its newest pupil.