George Phillips, a middle-aged Londoner, works as an estate agent for the firm of Frobisher, Rendell and Ross. His home life is soured by clashes with his wife over whether their teenage son's girlfriend should be allowed to sleep over at their house, a situation the timid, melancholic George dislikes but hasn't the guts to forbid. His professional life is dominated by his attempts to find a buyer for Sunley House, a once-fashionable 1960s office block which has lain unoccupied for over a year. When his wife leaves for Colchester to look after her elderly father, George avoids conflict with his son by sleeping over at Sunley House. Meanwhile, his workplace rival, a younger man called Rycroft, is also trying to find a buyer for Sunley House (and thereby usurp George's place in the firm). One morning George finds himself locked in and has to crash through a window to escape. When Rycroft finds the broken window, he sets out to find the culprit.