In The Murder of Roger Ackroyd by Agatha Christie, a widow's suicide stirs rumors of blackmail and a secret lover. The widow, Mrs. Ferrars, is rumored to have murdered her husband. Her death is initially believed to be an accident until Roger Ackroyd, a widower who had been expected to marry Mrs. Ferrars, reveals that she admitted to killing her husband and then committed suicide.

Not twenty-four hours later, Roger Ackroyd is murdered. The case involves blackmail and death, and Hercule Poirot comes out of retirement to solve it. Poirot discovers many secrets and motives, and the one who killed Roger Ackroyd.

The book is considered one of Christie's most controversial mysteries and breaks all the rules of traditional mystery writing. The conclusion of the book is perhaps the single factor that has earned it its reputation as the greatest mystery novel ever written.