Jo Miller and her boyfriend Grag Parsons arrive in Aidensfield to organize a peace demonstration at an abandoned air base which the Americans plan to reopen. They team up with local troublemaker Pete Grimshaw. But the police has gotten wind of their plans and Division asks Sergeant Miller to keep an eye on the demonstrators. That does not go quietly. PC Walker is accused of beating up Greg Parsons and Jo is arrested to Sergeant Miller's displeasure, because she is his daughter! The new vet Fergus is on his way to the zoo with a cobra in a box. On his way he stops at Bernie's garage for some petrol and to ask Rosie out. When he returns to his Land Rover he discovers that the snake has escaped.