Dex works as a gardener for Dr Jefferson at his home on Hexam place in Pimlico: an exclusive street of houses inhabited by the rich and serviced by the not so rich. The hired help, a motley assortment of au pairs, drivers and cleaners, decide to form the Saint Zita Society (Zita being the patron saint of domestic servants) as an excuse to meet at the local pub and air their grievances. When Dex is invited to join them, they find him to be a strange man, ill at ease - and these first impressions are compounded when they discover he has recently been released from a hospital for the criminally insane, where he was incarcerated for attempting to kill his own mother ...