Backbeat aims to pull off the intriguing feat of turning a footnote into the central focus. Adapted by Iain Softley (with playwright Stephen Jeffreys) from his 1994 movie of the same name, the show whisks us back to the early days of the Beatles when the Fab Four were a five-piece outfit (with Pete Best on drums) pounding out cover versions of American rock'n'roll in the seedy clubs of Hamburg's red-light district. It counterpoints the group's progress towards their first single and pole position for world domination with the fate of their original bassist, Stuart Sutcliffe. This so-called "Fifth Beatle" swapped the chance of pop stardom for a Hamburg art school and the love of the beautiful German photographer, Astrid Kirchherr, only to die of a brain haemorrhage in 1962, aged 21. It also explores Sutcliffe's influence on the forging of the group's identity.
One of the implications of the title is that the songs will serve principally as a background to the drama, which here centres on the troubled triangular relationship between Sutcliffe and the two people who loved him best – Astrid (a gravely lovely Ruta Gedmintas) and Andrew Knott's jealous, abrasive John Lennon who hero-worshipped him, perhaps homoerotically, and bullyingly insisted on his membership of the Beatles despite Sutcliffe's misgivings and lack of musical talent. It's easier to use music in that way on film, though, and while no one could accuse Backbeat of being just a jukebox tuner with pretensions, the drama often finds itself compressed into portentous, over-neat soundbites ("John wants the world and Paul will work out how to get it for him," Astrid warns Stuart).
The excellent band tear into such period classics as "Johnny B Goode" and "Good Golly Miss Molly" with a terrific jangly joy. If David Leveaux's dynamic blast of a production has no problem in evoking an impression of the Beatles' raw musical potential, it is less successful in persuading you that Sutcliffe, by contrast, was a lost genius. But then Nick Blood's cool and moody Stu seems to be in two minds about his vocation, the working-class rebel side of him disdaining painting as "wallpaper" for toffs.
"Love Me Do" was released a few months after Sutcliffe's death but Backbeat forgivably brings it forward so that he can have painfully mixed feelings about that too. By the end, however, any thoughts of the human collateral damage are lost in the overwhelming sense that the group is now unstoppable.
To 24 March (0844 871 7623)