Life is good for Jane Highsmith and Roland Fox: Jane's planning on taking over the local veterinary practice, Roland's second novel's been accepted for publication, and they are soon to be married. However, their wedding day is interrupted by a knife-wielding intruder. After confronting Jane in her surgery, she manages to inject the culprit with a microchip used for identifying pets. When a nearby petrol station is robbed by what appears to be the same perpetrator, DI Fellowes and DS Bright hope that the microchip will lead them to the suspect.