By the time the overture has started, the opera director’s job is normally done. Not if you’re Graham Vick, who spent the first night of Birmingham Opera Company’s latest production physically pushing the audience towards the next instalment of Mozart’s opera - that is, when we weren’t dodging the advance of amateur chorus members drawn from the local community.

Well, anyone used to one of Vick’s BOC shows knows the ropes: you’re in the middle, and anything can happen. In fact, we all had a role, too, processed as Trojan prisoners as we entered the former rubber factory that is the Sherborne Building.

Only after a truce was declared between Idomeneo’s Cretan acolytes and us pond scum could we roam free around the giant clods of earth and rusty lockups comprising Stuart Nunn’s designs.

But gimmicky this wasn’t. At the heart of this promenade Idomeneo lurked a frightening vision of mass hysteria. Here, the King faced with the terrible dilemma - to sacrifice his son, Idamante, to fulfil a vow made to Poseidon - is a Mao-like despot whose followers express their devotion through robotic routines and, to judge by the scraps of bloody flesh lying around, regular ritual slaughter.

The result is a crisis of authority.

“Where is the power to save me from myself?” demanded Paul Nilon’s powerfully sung and fiercely sympathetic Idomeneo in Amanda Holden’s hard-hitting translation. In admitting this vulnerability, he ends up cut off from his followers who might suffer Poseidon’s wrath when the King prevaricates - but subject him to a dreadful backlash when he decides to give up his son after all. The opera’s central dilemma, the complexity of moral responsibility, hits home incredibly hard.

The show doesn’t always stay quite as charged. The love triangle between Idamante, the Trojan princess Ilia and her spiteful Greek rival Electra doesn’t lend itself as well to Vick’s big-house treatment. But all three impress: Anna Dennis is an unusually powerful Ilia, full of wounded pride; Mark Wilde’s Idamante, though taxed by the florid writing, makes a touching figure; and Donna Bateman’s Electra muscles through with commanding tone and plenty of bitchy hauteur.

And with William Lacey coaxing appropriately wild sounds from the orchestra, this show is BOC at its best: memorable not just because of its community stars, but because their impact is indivisible from the whole experience.

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