Radiator takes place in a run-down, rubbish-filled, rodent-ridden Cumbrian cottage where Maria (Gemma Jones) and Leonard (Richard Johnson), an elderly married couple, reside. Leonard is ailing and bed-ridden, and Maria takes care of him, patiently attending to his demands and often irascible moods.
Following a phone-call from his mother that’s a tentatively-phrased cry for help, the couple’s son Daniel (Daniel Cerqueira) comes to the cottage to be of assistance. “You come here once every few months. That’s not up to snuff,” Daniel is reprimanded by a concerned neighbour of the pair. But as he settles into the cottage, finding himself a sometimes useful but equally sometimes unwelcome presence within the weird, makeshift routine that his parents have devised for themselves, a picture gradually builds of the past hurts that have affected Daniel’s feelings about his folks.