Dr Martin Ellingham makes his debut on the local radio station, Radio Portwenn. He’s not a natural in front of the microphone, and the interview is like pulling teeth for presenter Caroline. She’s furious with his monosyllabic answers to her questions.

Bert Large is in dispute with his son Al over his future in the plumbing business. Al desperately wants to change career. He’s determined to go to college to learn about computers and break away from the family business. His father won’t hear of it.

Their row prompts Al to leave, breaking his dad’s heart. Bert shares his woes with Martin, who tells him he fell out with his father too, and still doesn’t speak to him.

A nasty stomach bug is sweeping through Portwenn. People are dropping like flies, and filling Martin’s surgery. The local pharmacist has been busy with customers seeking remedies.

Martin decides he must try to track the source of the bug, and heads for the swimming pool. The staff assures him the water is checked rigorously.

But Martin tells them they must close the pool immediately. When they refuse Martin makes his own announcement to every one in the pool about something dangerous in the water. It creates mass panic as everyone tries to scramble out at once.

Martin’s theory loses credibility when patients who have never been near the pool develop symptoms. He makes a return visit to Radio Portwenn to warn people on air that the culprit is Portwenn’s water supply. Caroline is furious.

The last time the village had a scare about contaminated water supply it almost closed down. After the broadcast villagers are equally furious with Martin, and vent their anger on him as he walks away from the radio station.

Bert thinks he has the answer to the problem. He’s been bottling spring water as a side line, and presents a bottle to Martin to try. Bert claims it is from an ancient spring “”beneath the green hills of France””. Business is booming since Martin’s radio warning.