Spring Awakening is a bizarre compote of different ingredients that should never work and seldom actually does. Its moments of synthesis are rather marvellous, however, and the panache with which this production approaches it, even when they are very conspicuously absent, compensates for much of the incoherence that dogs script, score and concept.

The main substance of the show is Wedekind’s original play, from which this musical is adapted. This is a potent if at times hilariously overwrought exploration of adolescent growth, social repression and the wild, Dionysiac current of sex and violence that toss about its characters as they drift into puberty. On first inspection it seems ripe for conversion into something glitzier and more fun: our mores are neither so strict or so cruel as those Wedekind indicts in the play, and our view of adolescence is corresponding saner and less angst-ridden (though by no means angst-free). The play’s hysteria thus no longer makes complete sense. There is also a rich comic seam, both deliberate and inadvertent, that ought to nourish the witty smut many musicals need to flourish. It is well mined here, not least when the austerely cerebral Melchior is explaining, by means of ‘shall we say life-like diagrams’ (in his teacher’s later words) to the baffled and tormented friend Moritz.

W. H. Auden wrote that opera could never be sensible, because when people are sensible they do not burst into song. The grandeur of operatic music gives it the option of mad seriousness, instead. Faced with the same constraint, musicals almost always have to be silly (Les Mis makes an honourable exception; Phantom does not). That silliness is certainly present here, and at times it is delightful, sending up the desperate seriousness both of the young characters and their original creator. The scene just before the interval, when a poignant act of sexual discovery is serenaded by a chorus line of tuxedoes and scullery maids – like Frank Sinatra guest-starring on Upstairs Downstairs – is the best example, thought that when Moritz and Gabor earnestly talk over their troubles surrounded by girls reclining like Titian nymphs is also to savour.

This fruitful tension between serious substance and camp form peaks half way through the second act. Things deteriorate because it becomes horribly clear that the relationship can’t be sustained : there is too much darkness left in the script – suicide, contemplated suicide, accidental death at the behest of one’s own mother – for the musical send up to work. The riotous main number as Melchior is expelled for encouraging Moritz’s ‘corruption’ is hilarious – and brilliantly choreographed – but in the bleak circumstances, somewhat disturbing. When the show does grope at emotional seriousness, the music flounders embarrassingly. The last professedly thoughtful ‘The Song of Purple Summer’ is a sentimental dirge, while the lyrics, most of all at the funeral, descend into banality (a father is reproached about the ‘unspent Saturdays’ with his dead child).

All this is sadder than it should be because the production itself is so spirited. Theo Hughes-Morgan is wonderful as Melchior, singing powerfully and acting with a perfectly-pitched stolid tenderness, even if his female opposite number can be vocally thin. As indicated, the choreography is vigorous and often inspired. The adult characters are even flatter than their roles demand, but this cartoonish quality adds something in its way. The supporting cast can be splendid too – one thinks of the comic gay seduction scene. The sometimes monotonous score is played, at least, very proficiently.

It is an odd mixture than of dark moral charge, light-hearted camp and intermittently dreary rock music: the dish is very well cooked, but it is still an arsenic soufflé drenched in watery cream.