Aftersomeyearsoftension,Richard(CliveOwen)beginsasexualrelationshipwithhissisterNatalie(SaskiaReeves).Nowmarried,therelationshipprovesdangerouslyobsessional.Theirprivateintensity(&workingclassorigins)contrastwiththemiddle-class,inhibited,stuffypublicscenesweseeintheRichmondworldintowhichNataliehasmovedwithhermarriage.Astheguiltandintensityofthesiblingsincreasesweseemtobeheadingfordisaster,aforbodingwhichincreaseswhenNatalie'shusbandSinclairfindsout.