After two sell-out runs at Theatre Royal Stratford East, first in March 2006 then in February 2007, it's great to see reggae musical The Harder They Come loosen up the venerable old Barbican. You can almost feel London's soberest concert hall boogie on down as the exuberant cast, many from the original run, belt out classics including Higher and Higher and You Can Get It If You Really Want It. And as they sing, they snake-hip their way through shimmy-shake routines, small moves growing to big grooves, with the group dancing truly irresistible.

You wonder if Stratford East director Kerry Michael realised the show would be such a hit. Admittedly, there's a big market for pop-tune musicals (Abba, Queen, etc), and, as Harder is based on Perry Henzell's cult reggae film starring Jimmy Cliff, it features some all-time reggae greats.

But the Jamaican film, which is credited with bringing reggae to a world audience, also features a much darker tale of drugs and guns and innocence corrupted, themes that are painfully familiar to anyone who reads today's headlines.

Michael could easily have caved in and given his version of Harder a conventionally happy ending, yet by keeping the original he ensures the feel-good moves serve a serious purpose.

The Harder They Come is the story of wide-eyed Ivan who comes to Kingston with dreams of reggae stardom. He soon sees it's a cut-throat world, with every profit-carving shark after a piece of his talent. To avoid their clutches, he deals drugs - but drugs lead to guns, and guns to tragedy.

Rolan Bell as Ivan dominates every scene he's in. The young Hammersmith College-trained actor-dancer has an irrepressible energy and authentic innocence that are spot on for the lead role. His only shortcoming is a light voice, which is often overpowered by the excellent reggae band. No such reservations with Joanna Francis, who plays Ivan's sweetheart Elsa. This girl has the chops.

Also excellent is the sense of musical journey, from gospel to reggae, and the designs which ooze Seventies retro chic - the Afro hairdos are fabulous. Less good is the run time (it's a three long hours) and some of the movement direction, which looks stilted. By that I mean the cast don't always move with the jiving smoothness you'd expect. And the last quarter of the show needs pruning. Excepting these faults, The Harder They Come is a Caribbean cracker.

• Until 5 April. Information: 0845 120 7511, www.barbican.org.uk.