Successful professional London couple Sarah (Shirley Henderson) and Tom (Alan Tudyk) are in deep financial trouble. Their situation takes a terrifying and hilarious nosedive with the shocking behavior of their uninvited dinner guest Jessica (Indira Varma). Faced with the moral dilemma of their lives--and dragging their best friends Richard (Rufus Sewell) and Beth (Olivia Williams) with them--they make a series of choices that could be either their salvation or their destruction.