Oliver and Grace (Robson Green and Tina Hobley) have been best friends for years. Everyone wonders why they have never been a couple, and suddenly, so do they. Oliver is duped by his fiance just as they are about to set off on a romantic weekend away and instead of allowing the trip go to waste, he takes his best friend Grace. The couple use the time to explore the nature of their relationship and to discuss that impossible, perennial question: what does sex do to a friendship?
After a passionate weekend in the country they attempt to go back to their normal lives, but Oliver's fiance has her own agenda. It is not long before both Oliver and Grace are forced to make life-changing decisions.