Walking on Walls gets off to a good start. The set-up encourages curiosity as we find a man bleeding, gagged and bound to an office chair. Both the setting and his (apparent) captor also engage us, since this is far from a stereotypical hostage situation. Indeed the strength of this piece is really in its ability to hold suspense and keep the audience wondering right from beginning to end.

As one of the two characters has gaffer tape over his mouth for much of the piece, the first part of the play is essentially a monologue. Claire, played by Helen Mackay talks to her captive, gradually revealing to him, and so too the audience, the “who, why and where” of the scenario. But from the outset this is comedy, especially as Claire is so concerned for the welfare of her prisoner, reassuring him that the blow he’s sustained to the head is purely superficial. She’s likeable, sweet and vulnerable, despite her clearly crazy behaviour. The first five minutes are particularly well written by Morna Pearson, funny and detailed, with plenty of observational and relatable humour from office life.

There are more serious themes running below the surface though, which come clearly to the fore as the plot develops, in particular offering some significant reflections on the effects of bullying and a less significant but entertainingly topical reference to “killer clowns”. As a character, Claire can be a little far-fetched at times, but the script does bring a thorough characterisation and back story. Helen Mackay holds the part well and brings in both a comic and a moving performance, but has a tendency on occasion to be a little overly theatrical in a relatively intimate venue.

Walking on Walls has an unusual premise, wholly suitable as a lunchtime theatre piece. It offers light entertainment with plenty of laughs and some more considered and thought provoking moments.