In 1946, in post-war London, a chance meeting between the flamboyant Antonia Ashton (Helen McCrory - Anna Karenina) and the shy Rose Bell (Fay Ripley - Cold Feet), sets off a tortuous chain of events. Rose Bell is a put upon housewife, suffering under the bullying of her husband Barry, a decorated former RAF pilot. Rose so hates his mistreatment of her and his penny-pinching ways that all she can do is window shop and dream about another life. Antonia is glamorous, wealthy and in a passionate affair with a handsome lecturer called Vic, who to Antonia's horror is about to fly off to America and leave her. Rose and Antonia quickly hit it off and it becomes very obvious that they are both in unhappy marriages. Antonia is married to a very wealthy industrialist called Hector, who refuses to give her a divorce. Rose discovers that Barry has been having an affair, fathered an illegitimate child and now plans to cash in a hefty life assurance policy. At her wit's end, Rose calls Antonia and they get together to plot Barry's death before he can cash in the policy. Before Rose has had any time to really think about it, Antonia pushes Rose's husband to his death. Once the post mortem and funeral have been conducted, Antonia calls Rose to tell her that she now has to return the favour. Rose finds herself involved in another murder and one that may well mean her own demise unless she can find a way out.