Billy McCracken is a juvenile on the verge of delinquency. The First World War has filled Halifax with soldiers, sailors, and easy money. The waterfront is an ideal place for this mature-looking 15-year-old to hone his considerable talents as a card shark. To move him away from bad influences, Billy’s mother prevails upon an old friend to get Billy a summer job at the estate of Alexander Graham Bell in Baddeck.

The opportunity is lost on Billy, who, as the book opens, is fuming on the train to Cape Breton. He arrives at the Bell estate, only to learn his employer is a batty old man who talks to himself. Billy’s superior attitude and laziness earn resentment from almost everyone, but the genius Bell recognizes a spark of real intelligence. Gradually, Billy is drawn into the most exciting project on the estate, the top secret hydrofoil being developed to fight German submarines.

Eric Walters drew on historical facts from Bell’s life. His hydrofoil set a water speed record in 1919 that was unbroken for a decade. Billy is full of flaws. He cheats at cards, uses loaded dice, and is scornful of those around him. Yet he is a sympathetic character. Bell emerges as a very real person too – a quirky genius full of compassion, as he was by all accounts. The mystery itself is a bit weak. The identity of the German spy is easily guessed, and the hydrofoil itself must have been a better-kept secret than it appears here. These few quibbles aside, however, The Hydrofoil Mystery is a lively, well-told tale that will bring young readers closer to their history.