Kate and Geoff Mercer are planning to celebrate their 45th wedding anniversary with dozens of friends. The event is to take place soon in the community hall of Norwich, the town near which they live. A week before the party, Geoff receives a letter which, although he tries to hide it, obviously troubles him. When his wife asks him what is going on, Geoff tells her that the body of Katya, his first great love who disappeared fifty years before in the Alps, has just been found in a melting glacier. From then on, Geoff starts behaving more and more strangely and for the first time after so many years Kate asks herself who the man she married so long ago really is.