<p>Tom Swift, that prolific youthful inventor, is engaged in trying to help the Allies win WWI. After reading newspaper accounts of the British tanks, Tom takes a sheet of paper and sets out to design a better one from scratch. And fortunately, he can throw the whole family business behind his venture.<br /><br />He has two problems: First, his friends and acquaintances are questioning his patriotism because he hasn't enlisted as a rifleman for the front lines. Even his girl is worried his blood isn't true-blue. But that's because he is developing his tank in secret, and they don't know he's concentrating on winning the war the American way, with machines.<br /><br />The second problem is that the German spies have penetrated the secret of what is being built in the high-security shop on the Swift property. And they will stop at nothing to steal its design - not kidnapping Tom, and not kidnapping the tank itself, complete with crew.<br /><br />Tom and his buddies had better work fast, or the American riflemen are going to find the Kaiser's soldiers using American-designed tanks against them! (Summary by Mark F. Smith)</p>