While the covers of Superman at this point had no connection to the stories within, the cover of Superman 15 (March/April 1942) seems to reflect the Lightning Master story from the previous issue.
The first story in this book, by Siegel and Nowak, deals with a policeman whose gets blinded in a gunfight with hoodlums.
A woman gets killed in the shootout, and the blinded policeman is blamed.
Lois Lane believes that the man is innocent, and investigates the dead woman’s background. She runs into Jimmy Olsen, who is given a last name in this story. She learns that the woman was the ex-wife of one of the mobsters in the shootout.
Sure enough, the mobster killed his former wife, and blamed the policeman for it. Superman captures him, and the policeman regains his sight, by getting bumped on the head.
The second and third stories in the issue both deal with aggressive foreign powers. Although this issue was released after the bombing of Pearl Harbour, the stories contained were completed before those events. The second tale deals with an evil Asian nation, Napkan, and the third, by Siegel and Sikela, has an European country, Oxnalia, invading its neighbours.
Still, the art leaves no question as to what country Oxnalia is meant to be. That little moustache is all that is needed.
In both stories, Superman ends the nations’ militaristic aggression.
The Oxnalia story also includes the first time Superman utters the phrase “up, up and away!”