A musical about a man trapped in a cave is no more unlikely than a film on the same subject, and it’s odd that this ambitious 1994 off-Broadway show by Tina Landau (book) and Adam Guettel (music and lyrics) is now historically sandwiched between Billy Wilder’s Ace in the Hole and Danny Boyle’s 127 Hours.

As in the Wilder film, the true life story of the cave-explorer Floyd Collins, who was trapped under a boulder 60 feet underground in 1925 and died a few days later, becomes a media event, with a pushy young journalist, “Skeets” Miller (Ryan Sampson) getting close enough to the despairing Floyd (Glenn Carter) for a story but not close enough to save him.

The dank brick vaults in the Playhouse directly underneath Platform One at London Bridge Station are an ideal setting, well exploited by director Derek Bond and designer James Perkins, using the full depth of the space, scattering it with ladders and orange boxes. There’s a visible eight-piece band under Tim Jackson’s discreet musical direction, mouth organ and acoustic guitar prominent.

It’s an enjoyable occasion (the musical was seen, and admired, at the Bridewell Theatre in 1999) with some very fine songs that never quite hit home, and a well-organised narrative that highlights Floyd’s relationship with brother Homer (Gareth Chart), temporarily seduced by the film guys, and sister Nellie (a metallically winsome Robyn North, who sings beautifully around the blues and operatic edges of her numbers).

But too often you feel the music, straining unwisely for Sondheim-style credibility, is prepared to go so far but no further. A serrated lullaby duet, for instance, for Floyd’s father (Morgan Deare) and step-mother (Jane Webster), never clinches its own lyrical potential, and a lively trio for rival journalists is undermined by rapid (but not too clever) lyrics.

Floyd’s family are joined at ground level by surveyors and their boss from the Kentucky Rock Asphalt Company, film-makers, ever more journalists, and itinerant traders (The Pit and the Pendulum anyone?). The momentum builds to a vivacious carnival-a-go-go, fading into a beautiful fantasy reunion sequence before the cruel and cold conclusion.

Glenn Carter, once a magnificent JC Superstar, and original cast member in the London Jersey Boys, handles his difficult, immobile but moving role with charm and aplomb, and he sings more powerfully in the tenor register, which makes the opening sequence with its forays into baritone sometimes hard to hear as he scampers across the ground that will soon engulf him.

A lively cast does good battle with the band, who supply a pleasing variety of rythmic and evocative accompaniment in a score mixing blues, folk and country and that has almost everything except distinctive personality, take-off delirium and take-home melody.