For a play about human guilt, this ambitious piece of theatre was unusually light and airy.

There were times when one wondered whether this version of Patricia Highsmith’s novel, adapted to film by Alfred Hitchcock, was meant to be more of a comedy than a dark drama.

The play revolves around two Americans who, surprisingly, meet on a train and begin to discuss who they could do without in their lives.

They realise that if they each murdered the other person’s problem, nobody would ever suspect them – they would have no motive, a perfect alibi and they would be perfect strangers.

While psychopath Charles Bruno (Christopher Harper, Coronation Street) takes the conversation quite literally, Guy Haines (Jack Ashton, Call the Midwife) seems to forget all about it until something truly terrible happens.

Some of the performances were exquisite, such as Helen Anderson as Charles’s frail, devoted yet suddenly unforgiving mother.

Yet, it could be argued that too much emphasis is placed on Charles’s close relationship with his mother and not enough on Guy’s gnawing guilt.

Hitchcock’s movie is more effective in ruminating on the nature of transgression and remorse, and at times it seemed like the play spread itself too thin in attempting to cover so many strands of the plot.

A word, too, for the clever stage design and sound effects. The final scene in particular worked to great dramatic effect, with the beaming headlights of the train piercing through the smoke drifting into the audience.