In the Reynolds factory, where Mugg's gang works on airplane production, a mysterious saboteur is wreaking havoc. To uncover the culprit, Mr. Reynolds recruits Danny, who, along with Muggs, begins to investigate. Muggs becomes suspicious of Dr. Nagel, a respected figure, and enlists Danny's help to gather evidence. Danny pretends to be ill to get closer to the doctor, but this move puts them in grave danger as the saboteurs target them for elimination.
Flying Wild
A group of young factory workers become suspicious that a doctor running an air ambulance service is actually a spy, using his transport to smuggle confidential information from their plant to enemy forces.