The beautiful village of Melsonby, North Yorkshire, is rocked by the shocking murder of much-loved postmistress, Diana Garbutt. Police suspect her husband, Robin.
At trial, the prosecution says Robin was stealing from the Post Office. Evidence from the Horizon system is a key part of the case against him.
Robin Garbutt is sentenced to 20 years, but key evidence is missing. His DNA isn't on the murder weapon and data from the Horizon system can't be trusted.
