IF you’ve seen the first two instalments of Chris Dolan’s Bob Cunninghame trilogy – solo dramas written for the great Scottish actor David Hayman – you’ll know the protagonist. A former industrial shop steward, now retired, Bob is a socialist with the gift of the gab.

Indeed, in Time’s Plague (the final play of the series) we find him as loquacious as ever, despite the fact that he is in a hospital bed awaiting surgery. Bob is convinced that he won’t survive the operation, which will be conducted in the “Death Star”, as he, like most of his fellow Glaswegians, calls the Queen Elizabeth University Hospital.

What follows is a dark night of the soul in which, imagining that the corridor of the hospital ward is the West Highland Way, our protagonist traverses Scotland on foot. From Milngavie to the Highlands, Bob wonders at our country’s beauty and rails against the social injustices that disfigure it.

He tells us about his new friends in the adjacent rooms. He is particularly affected by Nour, an elderly Palestinian Arab woman who collapsed during a trip to Scotland to find her Glaswegian penpal of six decades.

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Nour was driven from her hometown of Yaffa as a child by Zionist militias in 1947. After many years living in a squalid refugee camp in Beirut, she ended up settling in London.

The daughter of an Arab mother and a Jewish father she hasn’t seen since childhood, Nour is possessed, Bob says, of “beautiful, sad eyes”.

When he’s not walking the imaginary West Highland Way or recalling his conversations with Nour, Bob is singing bleakly humorous versions of Elvis Presley songs. Either that or he’s reflecting on what is, he feels sure, his “one-way ticket” out of the “departure lounge” that is the Death Star.

As ever with Dolan’s writing for Hayman, the piece boasts rich strands of gallows humour and topical observation. We, the audience, stand in for Bob’s visiting relatives.

“Why are you here?”, our protagonist asks, with barbed sarcasm, before asking if we’ve only come to get warm, thanks to spiralling heating bills. As if Bob’s observations on the cost of living crisis aren’t topical enough, he was, on Wednesday night, opining on Monday’s ascension to power of Liz Truss.

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Next week, I’m sure, he’ll have a thing or two to say about the state-sponsored mourning of a hereditary monarch who has passed away like many a great-grandmother in her nineties.

Dolan’s script – less than an hour long though it is – is a rich tapestry of politics, history, existentialism and humanistic poetics. Hayman (directed tightly for Fair Pley production company by his son David Hayman Jr) responds to it, as he always does, with a thoroughly engaging combination of energy, bonhomie, anger and deep reflection.

At one point – quoting Samuel Beckett – Bob expresses the eternal human need to “fail better”. When it comes to raging against the dying of the light, a la Dylan Thomas, few actors do it better than David Hayman.

Touring Scotland until October 18: fairpley.com