Tanks are a new wartime technology, and as the US enters WWI, Tom uses his skills and his family's factory to secretly design and build a bigger, better tank, able to travel at twice the speed of British models, with heavier armor plating, ability to roll over wider trenches, and other innovative improvements. As war fever sets in, many young men are enlisting, except for Tom Swift, which raises many concerns that he is a slacker. Even his girlfriend begins to doubt him, but he has to be secretive even from her, as the Germans do their best to steal his secrets.