When I heard about this book I was fascinated to get hold of a copy to see what I would make of it. I had heard that the two authors are sisters who have been writing children's stories for over 20 years and this was their first, co-written, novel. What was even more incredible was the way they had written this book: with one live file that each could access and make changes to at any time. What a trusting, open way to work!

'The Shepherd's Song' is actually the story of a simple piece of paper – on which is written Psalm 23 (The Lord is my shepherd...) Just before being involved in a huge car accident Kate McConnell writes down the Psalm for her son, who has turned his back on God. Just before she loses the battle for consciousness she looks back over her life and remembers the conversation she had with a friend that week:

"I've been a Christian for almost twenty-five years, and I haven't accomplished anything. I can't point to one single person I've had an impact on, even in my own family."

Of course her friend puts her right – as a committed Christian she has also been involved in worship, making meals for people each week and writing down scriptures for people regularly. But Kate wonders if those are the things that matter most, when she can't get through to her own son.

God reminds her of the piece of paper with the Psalm on it when she is drifting towards unconsciousness. She is clinging on, asking God to help her get up and out of there so she can take care of her son and her husband. But then He brings each line back into her mind and helps her to realise that He has things covered – and she drifts peacefully into a deep sleep.

Her husband and son, on the other hand, are full of anxiety and frustration as they reach the hospital. Her husband, ever the fixer, is aggravated beyond belief when he is told all he can do is wait: "That wasn't what he wanted to hear. Waiting wouldn't achieve anything. He wanted to make strategic phone calls. Contact the right people. That's usually how he solved problems..."

Even in this first chapter the book made me take stock and think about how often we are quick to make things better, to do things in our own strength. And yet when the unexpected occurs, like an accident, what impact does that have on our lives? Do we turn towards – or away from – God? Do we trust Him or are our hearts flooded with doubts and questions?

The story then opens right out, and takes in country after country. That small piece of paper starts its journey at the dry cleaners that has Kate's son's coat (it is in the pocket that the paper is found). It then travels to a wounded soldier in Iraq, to a young Kurdish girl whose family is fleeing the country, an abused girl in Spain who tattooed every hurt onto her body as a way to deal with it, to a Kenyan runner in the Rome marathon; in all the paper reaches 12 incredibly different people – some who had experienced a relationship with God before but others who had never opened themselves up to Him. For each one, a particular line of the Psalm resonates most with them and effects them profoundly, changing the course of their lives.

Some of the earlier examples I found a little unbelievable – the response of the character seemed too quick, and the cynic in me thought it wouldn't happen like that. And then I felt my spirit checked – if one line reveals the love of God to someone's heart it can be transformed in an instant. From that point on I seemed much more hungry to hear how the paper would change another's life.

The narrative weaves cleverly from place to place, person to person and the authors have done a great job of adding the 'colour' to each person's situation and culture. It must have been difficult to set a story right the way round the world but they have done that very successfully (I read that they got people from each culture to read and check the relevant sections – and that attention to detail shows.)

They also manage to cover a huge amount of issues within the story plot – such as abuse, the loss of a spouse, moving country due to educational reasons, dealing with estranged relationships. And the beauty of the story is that it shows how God's hope can permeate each of those difficulties... I was also fascinated to see how the authors handled the subject of death – and felt they provided fresh insights into how to view it.

The story ends where it began – with the paper back with the family it originated from. And Kate is able to see how God had used her handwritten Psalm to touch so many people; including her own family. She sees from God's wider perspective and realises how God is a God of the second chance.

This book is unique and more than just an enjoyable read – I heartily recommend it. 'The Shepherd's Song' is published by Hodder and Stoughton.