John Adams’s latest opera to grace the London stage, Doctor Atomic tells the troubled and often troubling story of the Los Alamos research facility and the testing of the first nuclear bomb.

Though he still toils under the label, Adams is no longer the minimalist he once was. His music has tremendous depth, huge emotional range and varied instrumentation (albeit it is always recognisably Adams, no better or worse in terms of surprise).

He can do turmoil and he can do tranquillity (not that there’s much of that in this story). Doctor Atomic opens with the augmentations of machinery and closes with recorded voices; there are melodies of rending sensitivity music for the meetings between J. Robert Oppenheimer (Gerald Finley, pictured) and his wife, Kitty (an agile Sasha Cooke, right); the anguish required for Oppenheimer’s ‘Batter My Heart’ aria cracked even Finley’s bankably impeccable voice; and the countdown to the test detonation was one of the most intense few minutes of opera score I’ve witnessed.

But the music isn’t what I came away thinking about. The debate about the morality of the atomic weapon is conducted through documented conversations and correspondence, like Leo Szilard’s “j’accuse” letter – which essentially charged the Americans with being as bad as the Nazis they had just defeated – or Oppenheimer’s arguments with colleague Edward Teller (Brindley Sherratt, sonorous as per). Though the evident historical veracity of Peter Sellars’s libretto adds gravitas to the non-scientific scenes, and Adams and the singers manage to extract great lyricism from the more banal technical passages, it’s a close-run thing. ‘Stockpile’ is a word which just doesn’t belong in an opera. Ditto ‘icosahedron’ (though credit to anyone who can sing it in time).

It’s an impressive opera – almost by definition of its existence – in which the greatest coup is to generate the ambient feeling that the bomb is in fact about to be dropped, rather than simply tested. The moral edge would be significantly blunter if the audience were comfortably aware they were witnessing a bloodless event.

That said, if John Adams meant to convey sympathy for the moral plight of Oppenheimer et al. (ahem: Smyth, these pages, last week), I’m disappointed to report that he fluffed it. Amid their chilling, dehumanising jargon, and constant buck-passing, the borrowed poetry of the more soulful arias (Donne, eastern philosophy, Thomas Mann, etc.) convinces one of nothing more than that the atomic scientists were smart, literate guys. But so was Machiavelli. And as the device finally explodes, the scientists’ mugshots are flashed up like a giant Guess Who? board of war criminals. Trial by theatre-goers. Esh! Nasty.

Doctor Atomic, a co-production from English National Opera and the Metropolitan Opera, New York, is at the London Coliseum until March 20. Tickets: £10-£84. Tel: 0871 911 0200 (www.eno.org).