An affluent family living in an isolated lavish home in the Welsh mountains decides to host a dinner party to broker a business deal between their neighbor Mair (Lisa Palfrey), and a local businessman, Euros (Rhodri Meilir), who wants to buy the mineral extraction rights to Mair's farm property.
Cadi (Annes Elwy), a mysterious woman, arrives earlier that day in order to serve as the waitress for the family and their privileged guests that evening. Shortly after her arrival, things begin to take a strange turn.