This film is about American tank production and shows work at the Detroit Tank Arsenal in the 1941-1942 era. A shorter version of this film was released narrated by Orsen Welles.The film details the manufacture and use of M-3 medium tanks. Tanks are assembled and treads, motors, guns, and turrets are put in place at a factory. Shows stock of many parts required. At the end of the film, tanks stage an attack at Fort Knox, Kentucky.