Walt Disney was anything but The Perfect American, according to the dark and haunted portrayal of his last days in Philip Glass's new opera, which has just finished its premiere run at the Teatro Real, Madrid.
 
London audiences will have a chance to judge the opera's historical accuracy and (more importantly) dramatic effectiveness when English National Opera hosts Phelim McDermott's brilliant staging in June. The many fans of Glass's music may be surprised by his evolving idiom, which is now harmonically and instrumentally richer even than his previous operatic commission, Kepler (2009), and a world away from the ascetic simplicity of Einstein on the Beach (1975–6) which made his name and reputation.

These operas, and intervening musico-dramatic studies of Columbus, Galileo and Gandhi, have in common a turning away from narrative history, both real and retold, towards the dreams and visions that made each man famous, even 'great'. The Perfect American dwells not on the embittered and obsessed narrator of Peter Stephan Jungk's novel, a cartoonist sacked by Disney decades before, nor on the complex intersections of Disney's personal life, but on his own intimations of mortality and longing for a legacy – not just through his work but through the embryonic, even alchemical science of cryogenics, which in 1966 was a glint in a few rich men's eyes.

Extensively researched and psychologically acute as it is, Jungk's novel is not a history of Disney's last days, and the charges laid at his feet, of megalomania, racism, sexism, homophobia, adultery – I may have missed a few – give classical power to the fall of a great man. Curiously, while Glass in interviews has maintained his admiration for and sympathy with Disney – a man of his time, yet one whose genius transcended it to shape American culture for decades – his opera adds child cruelty to the charge list, when Disney throws out of his house an unexpected guest in the person of a small girl. Lucy is trick-or-treating at Halloween in Jungk's novel, but her owl costume gives Disney's daughter Diane a fright, and she demands that Lucy go. In the opera, Lucy has turned up a month late, on Walt's birthday. Apart from conflating two episodes for dramatic economy, it's hard to see what this metafictional confusion achieves, and the brief episodes of this 105-minute opera add up to a quick sketch of a monstrous egotist who wants to live forever. Can an opera on Michael Jackson be far behind?

Without permission to use any of Disney's trademark characters or animations, McDermott has deftly recreated a world of black and white, shot with shafts of improbable colour, always on the move. The video designs of Leo Warner and Joseph Pierce hint at Mickey and more as sublimations of Disney's own troubled nostalgia for his childhood, and Dan Potra's hi-tech set makes unceasingly inventive use of a pair of projectors. It's quite a show, at least as much at home in the world of music theatre as the old confines of 'opera' – which shines an even more unflattering light on the deficiencies of Rudy Wurlitzer's libretto. What was artful in Michael Hofmann's subtle translation of Jungk's novel (originally written in German) becomes a wordy mouthful when set to music, and Glass often leaves vocal and instrumental lines to go their own way.

This was no reflection on the cast, especially the tireless work of Christopher Purves as Walt, and the soft-centred bit-parts of his family, sung with enthusiasm and impeccable diction by David Pittsinger, Sarah Tynan, Janis Kelly and Marie Mclaughlin. Donald Kaasch hints at the shadow the cartoonist Dantine could have cast over the piece if he'd been allowed, and John Easterlin makes the most of a cameo as Andy Warhol. Best of all, under the baton of Glass's hugely experienced advocate Dennis Russell Davies, the chorus and orchestra of the Teatro Real brought expressive and timbral warmth to an idiom more often known for its chilly, metronomical precision.