Ria Lynch and Marilyn Vine have never met. Their lives have almost nothing in common. Ria lives in a big ramshackle house in Tara Road, Dublin, which is filled day and night with the family and friends on whom she depends. Marilyn lives in a college town in Connecticut, New England, absorbed in her career, an independent and private woman who is very much her own person.
Two more unlikely friends would be hard to find. Yet a chance phone call brings them together and they decide to exchange homes for the summer. Ria goes to America in the hope that the change will give her space and courage to sort out the huge crisis in her life that is threatening to destroy her. Marilyn goes to Ireland to recover in peace and quiet from the tragedy which she keeps secret from the world, little realising that Tara Road will prove to be the least quiet place on earth.
They borrow each other's houses, and during the course of that magical summer they find themselves borrowing something of each other's lives, until a story which began with loss and suffering grows into a story of discovery, unexpected friendship and new hope. By the time Ria and Marilyn eventually meet, they find that they have altered the course of each other's lives for ever.