King flies to Plain City, where "Nitro" has sent "invitations" to the police and others to attend the robbery of the First National Bank. The robber shows up right on time and threatens to detonate a container of nitroglycerin if he isn't given $50,000. He takes King as hostage to gain passage to the mountains, where he leaves King without his gun or boots. After he makes his way back to town, King is again confronted by Nitro, who plans to repeat the robbery in 24 hours. King and his companion, a girl named Aurora, find out Nitro's real identity, but Nitro forces the pair into King's single engine police plane and orders King to fly him to the coast. King overcomes Nitro, but on the way back Nitro dumps the stolen money out of the plane. King must go on horseback into a wilderness area, where he finds that the stolen money has been found (and spent) by a poor backwoods family.