Fourteen-year-old Sam travels to China with her mum, well-known protestor Dr Lee, science writer and pacifist. Chinese dissidents have proof of atomic underground testing in Tibet and scientific formulae which they want to smuggle out to the Western media.
Mum has carried out personal letters for dissidents before, but political maps or scientific formulae are a different issue. Officially that's spying, even if Mum believes it helps world peace to share scientific information. Worried, Sam starts imagining they are being watched, everywhere.
Sam wants to help her Mum, but is it her duty or just someone else's politics? Then Sam is pushed off the Great Wall by somebody who has mistaken her for Kim, who is possibly illegally trading $US on the black market.
Returning through Australian Customs, Sam pieces together the clues and there's a chase in the Customs Hall. No duty to pay on the anti-wrinkle cream which Sam buys for her mother at the Chinese Medicine shop, but maybe scientific ideas are not duty free?
