As students, Marianne Dillon and Clare McMahon become instant and unlikely friends. Marianne is spoilt, brazen and irreverent; Clare hardworking, modest and shy. But somehow they bring out the best in each other.

Marianne's generosity and Clare's steadfastness are the glue of a friendship that sees them through twenty-five years of love and loss, successes and disappointments, marriage and motherhood. The secret of their friendship, they believe, is that they are complete opposites.

But when a life-altering crisis hits their relationship - a crisis that involves their husbands, children and indeed the lives they have created - the crack that was there all along tears them apart.