Powder Town.

Young J. Quincy Pennant is experimenting with detonating explosives where the shock wave can be sent like a stone skipping over distances without hitting immediate targets, but able to destroy targets at a further distance away. He is sent to a "powder town", a rapidly growing city being built around an arsenal and munitions factory. Pennant falls in love with Miss Sally Dean who also lives at the boarding house but she has been paid by the leaders of the gangsters to steal the formula.