When widower Sidney Middleton is found dead in his cottage from carbon monoxide poisoning, Sheila Malory is deeply disturbed. After all, a reputable local tradesman had given the suspect wood-burning stove a clean bill of health the week before. Then there's the fact that his son, David Middleton, had been keen in recent months to pack his father away to a nursing home - Sheila's suspicions that this was no accidental death just won't be quieted...