Buried deep under Edinburgh, accessible only via a side street and past an inconveniently parked white van, Paradise in the Vault is the perfect venue for this chilling chamber opera. A father and daughter hide themselves away from the end of civilization, but are forced to choose who else, if anyone, to allow into their new-found sanctuary.Perfectly balancing atmosphere and lyricism, Matthew JH Pearson’s score is the real strength of the show. Rarely has an overture felt so integral to the following work. The use of leitmotifs and repeated ideas is effective but never heavy-handed, and I’m still haunted by the ominous rising semitone on the line ‘It isn’t safe’. Director Harry Benfield’s libretto is relentlessly naturalistic, yet never jars with the operatic vocal performances – the words and music fuse so perfectly together you can’t imagine them apart. Cleverly, characters trade modes of speech and melodic lines as they influence each other’s thinking.The four young performers dealt well with having to act and sing solidly for fifty minutes. A four-hander opera is never easy on voices, and you could detect some wear-and-tear in the vocal tone, but none of the actors lost a single pitch, and diction was impeccable. Jon Richome gave his character Robert the gravity of a man far beyond himself in years, and faithfully portrayed a tortured father juggling pride and love for his daughter. Playing his teenage daughter Sarah was the boisterous Ellie Jackson, again dealing well with a character whose age does not match her own. Yusuf, played by Jack Hamilton, spends the hour trying to join the others, and Hamilton’s inscrutable but seemingly earnest performance leaves the audience guessing as to his intentions. The tone of the opera changes entirely when Gemma Chance’s Delia interrupts with her Valkyrie-call, injecting the space with disturbed nervous energy and vocal acrobatics.The ending, whilst being a great plot decision, was not built up enough to be a point of culmination – I was surprised at its abruptness, but maybe that’s the idea. Given the hugely dramatic subject matter – the end of the world – the libretto and performers do well to save the show from being over-blown or Science-Fiction-like, focussing wisely on relationships and group dynamics. This opera has left its insidious mark on my consciousness in the best possible way, whether chilling or heart-warming I can’t decide.