William thinks he has a summer of mischief ahead of him until he discovers that his mother has arranged for him to spend the season working with an inventor by the name of Alexander Graham Bell. In a Nova Scotia outport, Bell and his crew are at work on his latest invention — a hydrofoil boat that will help the Allies defend the coast from the German danger. But there's a deadly menace hovering over the project and, suddenly, William finds his "boring"summer job transformed into an action-packed race to solve a terrifying mystery.