LEON SPARKS is from Mars. Ten-year-old Leon has been placed at Flintworne Junior School as part of a Top Secret student exchange programme. Leon joins class 5G, where he 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 its newest pupil 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?