It's 2015, in a disused warehouse in Digbeth. Two armed officers are pointing assault rifles at us. They're shouting. There's lots of shouting. We're nodding. There's a lot of nodding. We consider getting to our knees and placing our hands on our heads until they open their mouths and start to sing. We're watching our first performance by Birmingham Opera Company, up there with the most ambitious — and surreal — opera-makers in the world, their 50th production is a fortnight away, so we snuck into rehearsals. And, yes, it has all the hallmarks of the genius-meets-madness of their previous 49 shows.