A musical about a hero trapped in a cave 150ft below ground? It sounds about as likely as a song-and-dance version of Beckett’s Happy Days. This 1996 show by Adam Guettel (music and lyrics) and Tina Landau (book and additional lyrics) has won off-Broadway prizes and is now enjoying its third London production in the space of two decades. But, for all the sophistication of Guettel’s score, there were times when I felt as entombed as the show’s hero.
The simple fact is that I found about half the show’s densely textured lyrics hard to decipher. The fault may be partly attributable to the tricky acoustic in Wilton’s, although I’ve had no such problem with previous musicals at this address. Since others noted the same difficulty in a 2012 Southwark Playhouse revival, I suspect the issue may lie with Guettel and Landau’s failure to achieve the ideal balance between the words and the eight-strong band, here perched in the theatre’s balcony.
What I could glean from the long opening ballad is that Floyd was a young Kentuckian driven to cave-exploration by a mixture of visionary wonder and entrepreneurial instinct. The show is, of course, based on a true incident in 1925 and Floyd’s dream of fame was hideously realised when his entrapment turned into a media circus. While rescue attempts by first his brother, then by a sympathetic journalist and finally by a bombastic industrialist all failed, Floyd’s story became a national event, attracting 30,000 visitors to an obscure Kentucky field.

It is a fascinating story, but the show never seems sure what attitude to take to it. In part, it is a homage to the devotion Floyd inspired: he and his boisterous brother, Homer, imagine their future life together and their psychologically damaged sister, Nellie, has a profound faith in Floyd’s habitual luck. But the show is also intended as a satire on media exploitation, as hard-boiled newspapermen and an opportunistic film-maker arrive to make financial capital out of Floyd’s plight. The problem is that this side of the story was definitively explored by Billy Wilder in his 1951 movie, Ace in the Hole, with Kirk Douglas as a sensation-seeking hack.
Even if the show is uneasily torn beween sentiment and satire, the score is well worth hearing. Guettel may not have the melodic gift of his grandfather, Richard Rodgers, but he makes excellent use of Kentucky bluegrass, American folk ballads and modern dissonances in a way that fleetingly reminded me of Stephen Sondheim’s Assassins. Jonathan Butterell’s production also contains some striking performances. Although as immobilised as the hero of Prometheus Bound, Ashley Robinson makes you sympathise with the stoically suffering Floyd. There is also good work from Samuel Thomas as his extrovert brother and Daniel Booroff as an earnest Louisville reporter.
The standout performance comes from Rebecca Trehearn who, as Floyd’s sister, is both a model of sibling devotion and delivers a climactic dream song with bright-eyed fervour. There is much talent on display. I just wish this strange underground musical could be properly heard as well as seen.
• At Wilton’s Music Hall, London, until 15 October. Box office: 020-7702 2789.