Sorry, Wrong Number originally appeared as a radio broadcast starring Agnes Moorehead as Mrs. Stevenson. Many versions of this play have been performed, including a 1948 film adaptation. I'll begin with the version I'm most familiar with, the 1948 broadcast for the Suspense program, and then touch on variations.
The primary theme in most versions might be considered "mystery." A bedridden Leona Stevenson is waiting for her husband, Henry, to return for the office. She calls, but his line is engaged, so she contacts an operator see if they can help. The operator accidentally patches her into a conversation where a murder is being plotted against a woman who lives in a neighborhood not unlike her own. Leona attempts to report the plot to the operator, the police, and the hospital, but she is unsuccessful in convincing each party of the urgency of the situation. As the play progresses, the audience gradually discovers that the murder is being plotted against Leona.
In this version, suspense and foreshadowing act as the most significant literary devices. The audience is suspicious that Leona overheard a conversation that involves Henry, and details emerge that the murder will take place near Leona and Henry's home on 2nd Avenue. Tension is created through a series of clues that make it obvious to the audience that Leona will be the victim, but leave Leona unaware until it's too late. There isn't much substance to this version of the play without this suspense and foreshadowing.
In other versions, Leona is portrayed as a hypochondriac who comes from a wealthy family. Henry comes from a poorer background. Leona's father doesn't approve of their marriage and convinces a potential employer not to hire Henry. Desperate for money, Henry tries to convince an past employee of Leona's father, Mr. Evans, to help him sell narcotics to a Mr. Morano. At first, Evans refuses, but he is later overtaken with greed and decides to help Henry. Eventually, they decide to bypass Morano to earn more profit, but Morano finds out and demands compensation, reminding Henry that he has a wealthy wife and that an "accident" could occur. Henry decides he has no other way to come up with the money than to murder his wife. In this version, a major theme is the consequences of greed. Henry has a change of heart in the last scene, but he's too late.