Two of the four stories in Superman 5 (Summer 1940) are significant, both are by Siegel and Cassidy, but Shuster only does the pencils on the second, the Luthor story.
A rival paper, the Morning Pictorial, is introduced in this story, but falls into the hands of Axel Evell, a corrupt politician, who uses the paper to attack his foes and shield his minions.
This puts the Pictorial in direct opposition to the ever-honest Daily Planet, and Evell tries to buy the Planet from its publisher, Burt Mason. This is the first time we see the Daily Planet’s publisher, but he only makes one further appearance, in the next issue.
Unable to buy the paper, Evell sends his goons to disrupt the delivery, burning the trucks and threatening the vendors. Superman prevents his plans from succeeding, and scares his henchmen enough that they confess.
At the end, the Morning Pictorial returns to its previous owner, with George Taylor commenting on how important it is to have another paper in the city.
Luthor returns in a story that gives Superman a new power, one that would not remain a part of the hero’s repertoire.
The economy is at the core of this story, and it turns out that Luthor has been manipulating it, for the benefit of himself.
Luthor has addicted many prominent businessmen with a “narcotic incense,” making them his slaves. Although it is not defined beyond this, I would tend to think that opium would be the drug intended by that phrase.
Superman takes the place of one of Luthor’s victims, pushing his face into the form of the other man.
When Luthor reveals that he knows that its really Superman, he is able to change his features back through sheer force of will.
Superman frees Luthor’s victims from their addiction, and the economy starts to recover.
The indestructibility of Superman’s costume is first mentioned in this story, although it is credited to being of a fabric invented by Superman himself.
Luthor takes a break for a while, returning in early 1941.