The play humorously critiques the concept of charity through the actions of the Brewster sisters. Outwardly, they appear genuinely kind, offering help to neighbors and opening their home to strangers. They prepare soup for the ill, serve tea and cakes to the local preacher and police officers, gather toys for disadvantaged children, and provide shelter for lonely elderly men. However, these men must fit the sisters' specific criteria, revealing certain constraints in their charitable deeds.

For example, the sisters deliberately overlook the destruction caused by the war in Europe, finding it inconvenient because it might mean using "that imitation flour again," reminiscent of the first world war. Additionally, they are not fond of foreigners, preferring "good" American Christians, particularly Episcopalians. They extend their so-called "charity" to Methodists like Mr. Hoskins. However, their nephew Jonathan is not welcome due to his unacceptable behavior throughout his life.

The greatest flaw in the sisters' charitable actions is that they have murdered eleven lonely men who sought refuge in their home. They believe they know what is best for these men, thinking that only death and a proper Christian burial can grant them peace. They strive to make the deaths as painless as possible by using elderberry wine poisoned with arsenic. The sisters take pride in the fact that one of the men praised the wine shortly before passing away.

The audience, along with Mortimer, quickly realizes that the sisters are just as unhinged as Teddy, who is convinced he is Teddy Roosevelt. Teddy often sounds a bugle while enthusiastically charging up the stairs as if he were storming San Juan Hill. Although the sisters don't display such obvious signs of insanity, the community dismisses Jonathan's assertions about the twelve bodies supposedly hidden in the basement. Even Mortimer finds it hard to believe that his aunts could be involved with the body in the window seat, initially blaming Teddy until the sisters admit to their actions.

The sisters handle their latest murder with surprising nonchalance, telling Mortimer to "forget you ever saw the gentleman." They consider their actions entirely justified and continue with their normal lives. When Mortimer suggests they didn't inform Reverend Harper about Mr. Hoskins because of guilt, they argue that they concealed him simply because it "would not be very nice" for the Reverend to see a body during tea. Abby adds, "I do think Martha and I have the right to our own little secrets."

The family's history is riddled with madness, exemplified by Teddy's grandfather, a doctor who gained wealth by developing medicines, which he occasionally tested on patients with disastrous results. Jonathan is also afflicted by this family curse, having murdered twelve men and threatening to torture Mortimer to death. He claims his latest murder was warranted because the victim insulted him by comparing his appearance to Boris Karloff after Dr. Einstein's botched reconstructive surgery. This hereditary flaw makes Mortimer reluctant to marry Elaine until the aunts reveal, to his great relief, that he is adopted.

Kesselring humorously critiques theatrical norms and the critics who judge them. In this play, theater reflects life only in its most absurd situations. The farcical events ironically back Mortimer's claim that theater doesn't mirror reality, yet it undeniably provides entertainment. This is demonstrated through the strange situation Mortimer finds himself in while narrating the plot of a play he recently watched. He explains to Jonathan and Dr. Einstein, who are scheming to incapacitate and kill him, exactly how the villain captures the hero. Despite criticizing the characters for lacking creativity and realism, Mortimer doesn't realize he is mirroring the play's hero, inadvertently giving his brother the perfect plan for his deadly intentions.

Kesselring cleverly mocks the arrogance of theater critics through Mortimer, who constantly complains about the uninspired plays he must review. He gets his just deserts by not only helping Jonathan formulate a plan for his murder but also by suffering through Officer O’Hara's tedious recounting of the play he has written throughout the night.