Ex-squaddies Ally (Kevin Guthrie) and Davy (George MacKay) return to Edinburgh after a gruelling tour of duty in Afghanistan. However, both struggle to learn to live a life outside the army and to deal with the everyday struggles of family, jobs and relationships. Adapted from the hit musical based on the music of The Proclaimers, this is a journey north for a beery, teary, toe-tapping tale of home, heart and Hibernian FC.
If your knowledge of the bespectacled Reid brothers (aka The Proclaimers) and their back catalogue extends no further than I'm Gonna Be (500 miles), Letter From America and the 'aha' one from Shrek, the opening rendition of Sky Takes The Soul may come as quite a shock .
Originally written in support of Sri Lankan separatists The Tamil Tigers, now a meditation on death delivered by troops in Afghanistan, it immediately jolts you out of your musical comfort zone.
Sunshine on Leith is no 'Jock Of Ages' and up until the jubilant finale wisely avoids over-stylised choreography in favour of rowdy pub-based confessions and intimate declarations of love, all set against a tourist board's dream of Edinburgh.
Fletcher draws on his Bugsy Malone experiences to ensure the story doesn't exist just to serve the songs, and the tunes benefit from the mixture of male and female voices softening the Reid's trademark brogue, enabling the lyrics to shine through.
The young cast are uniformly excellent, ably supported by musical veteran Horrocks and the ever watchable Mullan as Davy's parents.
The only bum note is provided by Jason Flemyng in an underwritten role as Horrocks' smitten boss, gurning furiously and Dad-dancing around an art gallery, he's totally out of step with the otherwise naturalistic delivery.
The plot veers from Scotland to Soapland in the second half, courtesy of a convenient and contrived medical emergency but thanks to sterling performances and superb vocal work from Horrocks (whose interpretation of the titular track may leave some feeling a wee bit weepy), the melodrama is kept to a minimum and at the 500 strong, sing-a-long climax, it will be a cold heart that can't warm to this sunshine.