Janey Brown feels like she is practically invisible. With her stick-thin legs, mousy brown hair and grey eyes, no one ever notices her. Then a crazy woman turns up at the school gates, claiming to be Janey's godmother. According to hip-hop-talking, larger-then-life `G-Mamma', Janey Brown really is something special. She's Jane Blonde, Sensational Spylet - and it's time for her first mission...

Swapping her too-big school uniform for a silver spysuit, and her battered satchel for a set of amazing gadgets, Janey soon discovers that nothing in her life, or in her past, is as it seems. Her elusive Uncle Solomon happens to be the head of SPI (Solomon's Politicational Investigations) and the greatest spy the world has ever known. Recruited by the government to work on top-secret Project Crystal Clear, Solomon has made a scientific discovery that could change the world. But now he's gone missing. Can Jane Blonde get to him first? Or will The Sinerlesse, a rogue spying group with evil purposes (and a very nasty dog), hunt him down and take his secret?