This is a thrilling new adventure for Matthew Pryde...It is 1805, and England is in the midst of her war with France under Napoleon. Matthew Pryde, employed as engineer at a coal mine in Kent, is regarded as the perfect 'spy' to send across the English Channel to investigate rumours that the French are digging a tunnel underneath the Channel. Matthew is accompanied by the mysterious Mr Black - and the rather unexpected addition of the unconventional Kate Denton - to France where they must try to find the existence of a tunnel on the French side. What then follows is a treacherous journey across Republican France, and a close encounter with the Revolution's most effective form of punishment, the guillotine...