There's a cold snap in Pontypandy and Norman's pet lamb Woolly is freezing. Dilys won't allow Woolly to share Norman's bed so Norman decides to make the lamb a bed of his own from an old electric blanket - he doesn't realise the faulty blanket is a fire hazard. The smouldering blanket bursts into flames and Sam is called out to fight the fire. But a falling icicle punctures the fire-hose and Sam is forced to improvise.