Geoffrey Grey has been in prison for a year, convicted of killing his uncle, James Everton. Hilary Carew, his wife Marion's cousin, has a encounter on a train with one of the principal witnesses against him, Mrs Mercer, who seems regretful, distressed and deathly afraid of her husband. Hilary suspects she was coerced to lie at the trial, and impulsively decides to investigate. She begins with the trial transcripts.
Geoffrey claimed he had found his uncle dead in his study and picked up a pistol from the floor. Mrs Mercer, Everton's housekeeper, testified she had seen Geoffrey with the pistol only seconds after hearing the fatal shot. Geoffrey's motive was alleged to be anger that his uncle had changed his will, cutting him out. Since Everton's new heir Bertram and everyone else involved had good alibis, the case was open and shut.
Hilary interviews Mrs Thompson, the deaf neighbour, and Mrs Ashley, the daily help, but they only confirm the case against Geoffrey. Then Mr Mercer waylays her and tries to convince her his wife is out of her mind. Hilary goes to her still-smitten ex-fiancÚ Henry for help, and finds that Bertram has been saying the same thing to him. The coincidence seems suspicious. Anxious to speak to Mrs Mercer again, Hilary tries to track her down, but narrowly escapes being deliberately run over.
Meanwhile Henry, though still sceptical, has engaged Miss Silver, a professional sleuth. Highly efficient despite her prissy manner, she quickly uncovers irregularities in the Mercers' marriage, and solves the mystery of the changed will. Her next step is to break the seemingly solid alibi of the guilty party.
The review of this Book prepared by Maureen Evans