The difference between the many not the few, what David Hare “after Henrik Ibsen” labels humans and trolls, the latter of whom director Jonathan Kent depicts as pig-nosed Bullingdon Boys gorging at the gargantuan sloping banquet table of Richard Hudson’s epic set, is that whereas both are encouraged to pursue the worthy goal of “to thine own self be true”, the few are said to do so with the added venom to “damn the rest of the world”.

And after returning from active service to his humble croft in the woods of Dunoon, it is this selfish course of action which the “serial fantasist with attention deficit disorder” Peter Gynt (James McArdle) chooses to dedicate the remainder of his threescore years and ten.

Not for him a life of mediocrity in the provinces limited by societal expectations and the opinion of others – “If I can’t be exceptional,” he boasts to his loyal if disbelieving mother Agatha (Ann Louise Ross), “I don’t want to be.” – but a “front page splash” who will live long in the memory of all who read his tale, regardless of how tall it grows and how far from his inner truth it strays.

After drawing cries of “dick head” and later “loathesome prick” for kidnapping his former admirer Ingrid (Caroline Deyga) on the night of her wedding, Peter heads for the hills, first to avoid the wrath of her wealthy father who is joined by a gang with a grievance, and second to make as much money as possible so that he can support his love-at-first-sight soul mate Sabine (Rehanna Macdonald), the initial wooing of whom it has to be said is far too fleeting to take root.

Thereafter, what can only be described as a series of trips, both geographical and hallucinogenic, unfold in technicolour splendour as Peter seeks to find meaning and purpose through increasingly outlandish means: from a whiplashing orgy with a trio of troll-baiting cowgirls and the pursuit of obscene wealth courtesy of a duplicitous arms deal with both sides of a religious divide; to a short-lived thirst for spiritual enlightenment and a long-in-the-tooth burst for a return to nature.

But when he comes face to face with the devil in disguise as a man of the cloth (Guy Henry) and his imminent death at the hands of a moulder of buttons (Oliver Ford Davies) who reduces his “front page splash” to “a life of small encounters”, Peter belatedly concludes that it was perhaps not self-improvement but self-discovery that he should have been pursuing. And that for all his globetrotting and truth-twisting, it is the faith, hope and love of the girl by his side that can, to quote Orson Welles, “create the illusion for the moment that we’re not alone.”

Everything about this co-production between the National Theatre and the Edinburgh International Festival is epic. From the running time (200 minutes) and cast (25 and counting) to Richard Hudson’s impressive set design and Ibsen and Hare’s wild imaginations. And though the meandering and fantastical nature of the plot is not without its faults – some left, others snored – the real star of the show is the star himself, James McArdle, who commands the stage with the swagger of a matador and charms the audience with the ease of a seasoned comic. Proving that, unlike Peter Gynt, he is a master of both style and substance.

Peter Callaghan