The friendship between Emma Morley and Dexter Mayhew begins on the day after graduation - the morning after they have spent the night together.
It is July 1989, a year after Emma and Dexter first met - and agreed to be 'just friends'.
Dex is off travelling in India and Em has slid into a grim waitressing job at a Mexican restaurant.
But their letters continue to fly back and forth.
Dexter's career in television seems to be taking off, but, as they move into the early 1990s, Emma is still wondering what to do with her life - a dilemma not eased by Dexter's endless parade of girlfriends.
Alcohol is beginning to take over Dexter's life, but the frenzied world of media partying seems to need that kind of fuel.
His old friend Emma has qualified as a teacher and has begun to shake off her romantic feelings for Dex.
Emma has bought a flat with her boyfriend Ian, and is drifting away from Dexter and his drug-fuelled lifestyle.
Can their friendship bridge the difference between their worlds?
It is now 1996 and the two friends have not spoken to each other since a painfully acrimonious evening the previous summer when Emma found herself admitting that she no longer liked Dexter very much.
In the meantime her teaching career is surging ahead while Dexter is being edged into the graveyard slots of TV presenting.
Dexter has fallen in love, a fact which he feels compensates for his almost negligible career in television.
Meanwhile his old friend Emma has quit her teaching job and secured a small advance to write her first book.
Their friendship has deteriorated to a functional acquaintanceship.
Dexter and Sylvie have got married and embarked on their new life together, and Emma is quietly becoming a success in the world of children's fiction.
They are back in touch but their worlds are miles apart.
Emma and Dexter have surrendered to their desire to be together, and while ostensibly maintaining separate flats they are living at Dexter's old bachelor pad, trying for a baby and house hunting.
The pressure is on.
Seventeen years after the one night they spent together in 1988, memories of that fateful day are still strong - perhaps even stronger, given the events that have shaped and changed their lives for ever.