In Matthew Lenton, playwright Douglas Maxwell has an ideal director: with a script that floats in and out of the hero's consciousness, mashing up a metaphysical world of fairytales and a brutally naturalistic Glasgow of dubious pubs, antiseptic hospitals and children's play centres, Charlie Sonata is at once a magical journey through one aging and alcoholic man's bid for redemption and a harsh study of social failure. As his friends attempt to negotiate maturity, Charlie 'Chick' Sonata has remained stuck in the past, clinging to the bonhomie of the University bar. But what promised a life of freedom and autonomy in 1994 has increasingly become an embarrassment, and Chick's romanticism alienates him from both the friendships and any sense of purpose.

Sandy Grierson – who has become the actor for any iconic Scottish figure – lends Chick an air of vulnerability, playing up his compassion and incoherence. As the emotional heart of the play, Grierson reconciles Chick's boorishness and moments of clarity, bringing out the detail and kindness of Maxwell's script. Lenton's direction, capably shifting between surrealism and realism, evokes the drunken stupor of Chick's journey, balancing a hero's journey mythology, through the support of Meg Fraser's Meredith, with the ugliness of Chick's descent into the underclasses.

The use of a narrator holds together the story – Meredith's subplot, involving the poisoning of a Latvian choreographer and her impulse towards suicide, is developed more as a thematic echo to Chick's adventure – while Ana Ines Jabares-Pita's design pushes the surrealism through a visually delightful scenography. The tensions in the script – Chick's need for responsibility and his failure to achieve it, the longing of the characters for their own carefree pasts, the competing attentions of self-interest and family or friendship – drive the plot through encounters with manipulative Londoners, cynical surgeons, disapproving partners and, most immediately, his relationship with alcohol.

If Chick's redemption moves heavily into the metaphorical, it is the episodes of naturalism that are most dynamic, as he spews in the kitchen, loses the ability to speak and finds himself bullied by characters from the margins of society. Charlie Sonata juxtaposes the fantastic and the mundane, drawing attention to its theatricality before delivering vicious slices of recognisable traumas. With Vanishing Point, Lenton has demonstrated his mastery of such liminal stories, and Maxwell's skill at combining the vernacular with the philosophical conjures a protagonist who is both pathetic and sympathetic.

Royal Lyceum Theatre, Edinburgh, until Sat 13 May.