A man stands silhouetted in the light from an open door, half-singing, half-talking to himself. Solo, repetitive, gruff, swaying, twitching, bags under his eyes, greying hair, rubber sneakers and thousand-wash jeans. He seems to be waiting for his words to fall into place, like someone half-heartedly shuffling the pieces of a jigsaw puzzle. The not-so-quiet voice over my shoulder tells me this is how Chris Martin will look when reality finally catches up with him.

John Hannah is on form as the erstwhile frontman (also John) of Riflemind, the eponymous and defunct band of Andrew Upton’s 2007 play. More or less at peace with the fact that his rocker days are behind him, John now lives the tofu life in the countryside, accompanied by his remedially banal wife, Lynn (Susan Prior), with her pastel clothes, yoga and low-fat mayo.

Then the band shows up. A weekend in John’s country mansion, talk of a reunion, drugs, tetchiness about money, some bearding of the lion in his studio, viz. when he last picked up a guitar. Banter, chaos, laughs, recriminations.

So why’d they split? Dunno, and it doesn’t much matter: it’s the same as in every other ‘rockers reunited’ tale, it seems. There’s the overlooked-genius guitarist (Paul Hilton), wary of the foibles of his frontman, and his girlfriend, who wants to use a reunion tour to promote his solo album. There’s the young ringer (Joseph Kennedy), drafted in for that breath of fresh air. There’s the oik manager (Jeremy Sims), who wants to make loadsa cash, right, and shag groupies. And there’s the fat drummer (Steve Rodgers).

Trapped by their once-famous sound, the band inevitably chase their tails, trying to solve the riddle of forming Riflemind afresh and/but keeping it the same. “Nothing’s as good the second time . . .” Is it worth it? they’re soon wondering. And the answer, it turns out, is no.

Philip Seymour Hoffman has done a decent job as director, and the well-chosen cast is in step throughout; but there are major problems with the play itself. Riflemind isn’t eventful (or musical) enough to be The Doors, nor funny enough to be Still Crazy. Neither does it have a theme. That rock ’n' roll living isn’t all that liberating? That you get a little wiser and sadder with every passing year? Are those even themes?

Barring the opening soliloquy and some amusing sex on a sofa, there are no memorable scenes; there is way too much conversation — most of it un-entertaining, however accurately it reflects the hackneyed sentiments pervading most rock lyrics — where there might profitably have been action; and ultimately the play feels half finished, as though Upton thought that having simply created the members of Riflemind he could leave them to take care of the rest.

A man stands silhouetted in the light from an open door, half-singing half-talking to himself. He seems to be waiting for his words to fall into place, like a playwright hoping that they will knit themselves into a story.

Riflemind is at London's Trafalgar Studio 1, until January 3 next year. Seats: £25-45. Tel: 0870 060 6632 (www.theambassadors.com).