Catherine Saint John-Burke is a sophisticated British woman living an independent life in London's Chelsea neighborhood. But one day her world is turned upside down when she comes home to find a mysterious New Zealander named Shirley Zachary drinking beer on her sofa. Shirley announces she is Catherine's long lost half-sister. As far as Catherine is concerned, the only thing that Shirley has lost is her mind! Undaunted by Catherine's doubts, Shirley claims that their dad?whom Catherine thought had died before she was born?is still alive, stuck in the 1970s, and trying to seize ownership of property they inherited from their mothers. Now this odd couple must team up and track down their con-man father?and claim their rightful inheritance. Through the twists and turns of their journey, they ultimately discover the true meaning of SISTERHOOD.