The most interesting stories are those that break convention. The parable of the Prodigal Son is one of the greatest

Chekhov famously said that if the audience sees a pistol hanging from the wall in Act One, it has to be fired in Act Three. It’s one of the first and most important lessons you learn as a writer. Stories need endings just as chords need to be resolved. The murder is avenged. The mystery is solved. Love is requited, or tragically unrequited.

In 1969 in Glasgow, James Nelson murdered his own mother. What’s the proper ending for that story? A life spent in jail haunted by her ghost? In fact Nelson served his time, studied theology and applied to be a minister in the Church of Scotland. He was not a spectacular penitent. He didn’t give inspirational talks about his conversion or describe himself as the greatest of sinners. He simply challenged his Church to demonstrate its belief in the possibility of redemption.

The Church rose to the challenge. He found a parish. When, 10 years later, the press tried to rake up and sensationalise the story, his parishioners wrote letters of support to the papers.

Of course, a Church recognising that a sinner can repent and believe in the Gospel is not the same as a victim – or the parent of a victim – forgiving someone who has sinned against them personally.

A national Eucharistic congress will take place this September in Liverpool: a city that is still haunted by the murder of one child – Jamie Bulger – by two others. The continuing pain of that story disturbs our senses and seems to have no ending.

And just as the unresolved chord jars your brain, so the lack of a satisfactory ending produces rage. If you look at social media, you get the sense that, for many people, the only real ending would be a death sentence for the killers. Certainly the opposite ending – forgiveness – seems too much to ask of the boy’s parents. The title of his mother’s autobiography, I Let Him Go, seems to suggest that she has not yet forgiven even herself for her own tiny part in his loss.

I spent many years putting together a film about “the Railwayman”, Eric Lomax, who was tortured while a prisoner on the infamous Burma railway. That feeling that the story was not over left him unable to function emotionally until he had confronted his torturer, Nagase. When he did so, all his rage fell away and he and Nagase became friends.

That’s the story as I told it.

Once the film came out, however, I became friends with Eric’s daughter Charmaine. I discovered that to her, the sentence I’d so blandly said so often in pitch meetings and auditions – “he was unable to function emotionally” – meant years of living with a chaotic, untrustworthy father who had, in turn, undermined her ability to form relationships.

Eric Lomax also needed to be forgiven. The rule of Chekhov’s pistol really comes down to the fact that – morally and emotionally – actions have consequences. One thing leads to another. Thus the torturer reaches through his victim to torture the next generation. We are bound by the chain of events – unless the chain can be broken. And by and large, it is broken not through moral effort, but through grace.

One of the other victims I spoke to while working on the film of The Railway Man was a Dutch prisoner who had successfully hunted down his torturer. When he finally confronted him, the torturer had a heart attack.

You might think that this was the perfect ending, but in fact his former victim rushed to give him CPR and phone an ambulance. When the torturer’s family turned up, the man was, much to his own surprise, sitting at their father’s bedside, a hero – and he was trapped in this heroic scenario from then on.

I love this story. I love the way his own instinct to save kicked in and changed the ending. And where did that instinct come from? In Newtonian physics, actions lead to reactions. But thanks to Einstein we know that, though this appears to be the case in daily life on Earth, it is not the whole story.

A well-turned story is one in which the pistol we saw in Act One is fired in Act Three – in a way that one hopes is both satisfying and surprising. But there’s another kind of story – far harder to tell – in which the gun does not go off. Just as there’s another view of the universe in which things are weightless and time is not a relentless tick-tock countdown to the grave.

At the end of Sir Gawain and the Green Knight, for instance, the Green Knight refuses to take his revenge on Gawain. And most extraordinary of all, at the end of the Prodigal Son, the father does not punish his son but – in a sentence that Ernest Hemingway said was the most beautiful ever written – runs to meet him.

It’s worth remembering how unexpected that ending is. The son was not looking for, or hoping for, forgiveness, but only for a job. The fatted calf, the cloak, the ring … now that’s what you call a twist in the tale. Forgiveness is always a surprise ending – at least for the Prodigal and for his better-behaved brother.

The father, though, was waiting, standing where he could see the figure approaching on the road. The father always knew that the story was not over, that a different kind of ending was coming, one in which the chains of consequence, time and gravity would be severed and he would run towards us.

Frank Cottrell-Boyce is an author and screenwriter. This is an extract from Adoremus Extra, a lasting resource for cherishing the Eucharist, published by Redemptorist Publications, featuring contributions from over 40 well-known writers. For more information call 01420 88222 or visit rpbooks.co.uk/Adoremus2018.html

This article first appeared in the April 20th 2018 issue of the Catholic Herald. To read the magazine in full, from anywhere in the world, go here