After his "wonderful airship" crashes near St. Francis of Assisi's Home for Foundlings in Quebec City, Ben Franklin is thrown slightly off course in his carefully laid plan to coax Canada into joining the Americans in their fight against England's rule.

A motley crew of orphans hides the famous inventor from the British Redcoats during the American War of Independence. One of these orphans, 16-year-old Michael Flynn, is deaf and was abandoned by his parents, who were convinced that his problem was caused by demons who "seized his tongue and prevented him from speaking." Michael leads his best friends, White Rat and Briony, through the dangerous spy portals of underground Montreal carrying secret messages to ensure Franklin eludes the gallows. When Michael's sign language inspires the great scientist to create a top-secret spy code, Michael and his friends are flung headlong into an adventure they'll never forget.