After World War Two, an unknown number of senior Nazis escaped Europe and the Nuremberg Trials to assume new identities in South America, mainly in Argentina. A vast secret network gave them shelter in a succession of safe houses until the coast was clear to start a new life.

Alex Jones’ harrowing new play takes place in one of these Argentinian safe houses, where Mr and Mrs Schultz have taken refuge with Hanna Richter, who wears her Nazi sympathies on her sleeve.

That’s the set up for an evening of tension, mounting to an almost unbearable and protracted denouement. It’s hard to discuss the play without giving away the plot, and I wouldn’t want any prospective audience member to experience it knowing much more than I did. Suffice to say the clues are there for those who can read them, starting with the opening music, a Yiddish folk song “Donna”, contrasting the predicament of a calf bound for slaughter and a swallow flying free in the sky.

Three powerful performances and Ade Morris’s well orchestrated production concentrate the attention, despite the length of the evening.

Michael Strobel’s Oscar Shulz takes us on a chilling journey to the heart of a man who shows compassion to animals in a slaughterhouse and refuses to eat meat, while sanctioning and rejoicing in the murder of six million human souls. This complex character has the sort of attitude to smoking that the contemporary pro-smoking lobby calls fascist, while harbouring sexual proclivities which would almost brand him a paedophile.

Nicola Delaney makes the devoted wife, Lotte Schultz sympathetic and believable. She skilfully assumes the persona of the apparently fluffy airhead hiding the damage behind a cheerful, brittle front.

Emily Wood has perhaps the most difficult task - and journey - every evening. Her enigmatic intelligence and Hanna's ardour for the Nazi cause hide a secret which provides a climax so shocking and so graphic that it was too much for some audience members on press night.

In a programme note, Jones declares that history is an important teacher. He refers to the lessons we can learn from the holocaust. It seems from subsequent events in the Balkans and in Rwanda, that we are poor students. It’s theatre’s job to reinforce the lesson, and maybe Home Counties audiences need to confront these horrors. But I question whether such an unrelenting onslaught is the most effective way.

- Judi Herman (reviewed at the Watermill, Newbury)