The day of Nick's and Jo's wedding has arrived. To calm his nerves Nick takes a ride in his car when he is flagged down by a woman because of an accident. Suddenly the woman drives away in his car and Nick is stuck miles away from everywhere on the moors with an injured man on his hands. He manages to get the man to hospital, but time is getting short if he has to make it to the church in time. Sergeant Blaketon's day of retirement is nearing and he has applied for a year's extension of service, but the news from his medical exam is not good. News is not all bad though because they will also get a new police constable in Ashfordly.

Sergeant Craddock has been promoted and a new sergeant is expected at Ashfordly police station. His name is Dennis Merton and he is an ex-CID. From their patrol car PC Ventress and PPC Nicholson spot the disqualified driver Paul Rogers going in the opposite direction in his car after seeing his girlfriend Sandra, but Rogers denies having been driving when they confront him. His father Ken Rogers has had CID chasing his tail for years, and by going after Paul the Ashfordly police land themselves in the middle of a major CID investigation. David is out of form from sitting in the taxi and wait for customers. Vernon Scripps supervises David's training and spots the talented boxer Jeremy Purves. Scripps has high hopes for his new protégé, but despite his talents Purves lacks the deciding punch.