Confronted by a series of crashes as a result of testing the jet propelled Flying Wing, which the US Army had under close scrutiny, Hop and Tank began a thorough investigation which thus far has netted them absolutely nothing, except two vicious attacks on their lives! Circumstantial evidence points heavily to Carla Davis, a spot welder and trusted assistant of Simon Gore, the designer of the flying wing - and when they overhear her talking to someone in secret, their suspicions are heightened further...