The truth about the party on the island is now partially revealed, since the recorded voice clarifies the hints that Christie has dropped so far about her characters’ shady pasts. Now we know that they not only all have secrets, but that they have all committed murder in one form or another. We also learn that their host, whoever he or she may be, has a dark sense of humor and delights in tricks and word games. The name “U. N. Owen,” or, as Wargrave translates it, “unknown,” is a play on words. Additionally, the title of the record that announces their crimes is “Swan Song,” a term that refers to the sweet song supposedly sung by dying swans. The host’s central and most perverse word game involves the “Ten Little Indians” poem, as becomes apparent after a few murders have taken place.
Most of the guests stoutly deny the accusations made against them. As the novel progresses, however, these early denials begin to break down under the strain of the situation, and one after another the characters admit their guilt to each other. It is telling to watch, in Chapter IV, the way each deals with the allegations against him or her. Most of the guests deny the charges, but the ones who do so the loudest, we realize, are actually the people most wracked with guilt. We see earlier how Vera, Macarthur, and Armstrong, for example, are haunted by memories of their crimes but now claim to be innocent.
Meanwhile, the people who seem to feel no guilt over their alleged crimes manifest different reactions. Lombard, who throughout the novel never displays remorse for anything, willingly admits to leaving men to die in the wilderness. He sees no problem with having self-preservation as his highest value. Similarly, Tony Marston readily owns up to running down the children. A complete egotist, he seems to regard the incident chiefly as an inconvenience for himself, since his license was suspended. Emily Brent, for her part, refuses even to speak about her incident, which reflects her intense sense of propriety but also her powerful conviction of her own righteousness. She is not a criminal, her mind tells her, but virtuous and pure, and so there is no reason to even bother denying the charges, which she finds too ridiculous to trouble her.
The self-righteousness of some of the characters reflects their position in the social hierarchy. Emily Brent does not care about the death of her former maid partly because her maid is not her social equal. Similarly, the attractive and youthful Tony Marston inhabits the top tier of the social hierarchy; he is wealthy and frivolous, and feels no remorse for killing children who live in what he describes as “some cottage or other.” Those on society’s lower tiers behave more meekly in the face of the accusations. Mr. Rogers, for example, continues to perform his duties as butler even after Mrs. Rogers has fainted and she and her husband have been accused of murder. Even as the situation on the island deteriorates, constricting social hierarchies prevail.