As a heatwave puts Pontypandy's haystacks at risk from spontaneous combustion, so Sam invents a special thermometer for taking a haystack's temperature. The Tarzanesque jungle cry of Norman Price raises the alarm when the twins get caught in such a blazing haystack.

Norman rigs up a wind-powered skateboard to help his with his newspaper deliveries. Sam is busily repairing the inflatable pontoon which the fire crew use for rescues on water. When Norman's kite carries him away and dumps him in Pontypandy lake, the twins raise the alarm.