When Tom Barnaby has his constable sit in on the murder trial of Annie Woodrow, the reports he gets back start him thinking that he may have made a mistake in assuming Annie's guilt. She is all-but-assured to be convicted of bludgeoning to death of an old school friend, as a reliable eye-witness puts her at the scene, and she was caught in a web of lies when questioned. But Tom feels that things don't really add up, so he and his constable keep investigating as the trial proceeds.