It's July 1976 and London is in the grip of a heatwave. It hasn't rained for months, the gardens are filled with aphids, water comes from a standpipe, and Robert Riordan tells his wife Gretta that he's going round the corner to buy a newspaper.

He doesn't come back. The search for Robert brings Gretta's children - two estranged sisters and a brother on the brink of divorce - back home, each with different ideas as to where their father may have gone. None of them suspects that their mother might have an explanation that even now she cannot share.