What would it be like to have a friend from outer space? Ten-year-old Leon Sparks has been placed at Flintworne Junior School as part of a Top Secret interplanetary student exchange programme, where, it is hoped, he will learn the vital skills that will help save his race. Leon makes friends with the other children on his table, Lucy, Emily and Dominic. But when reports of strange lights over the school appear in the newspapers, shadowy foreign agents develop a keen interest in the school and its newest pupil, and they hatch a plan to seize Leon and his comportal, a device like a mobile phone but with greatly superior capabilities. Will they succeed in stealing him away? Or have they underestimated Leon's powers, and the resolve of his friends to stop them before it is too late?