The three sisters of Castleknock House live in seclusion. Their father has warned them that the world outside is dangerous: full of people ready to hurt and kill them. Now he is dead, and they are thrown back on their own resources. Eldest sister Fran believes that if they stick to their security routines – including the beards – they’ll be ok, but there are doubts among her sisters. Maybe the world outside isn’t that bad after all?

The three characters are nicely drawn: Fran is strict and hidebound by her father’s rules, Jo is the adventurous middle sibling, whereas the youngest Ger is naive and enthusiastic, having barely experienced anything outside at all. Fran masterminds a regime entirely focussed around staying safe, and taking no-nonsense to whole new levels. When she catches Ger dancing, she warns her that the music has not been created for pleasure, but to aid in their work-outs.

Jo makes the sorties for supplies into the outside world, and starts to doubt it really is as bad as she's been told – after all, she’s seen people smiling. As Jo becomes disenchanted with Fran’s strictures, the tension between them grows, and Ger is increasingly torn between her sisters.

The knockabout comedy of the the first half is very well executed; the interactions between the cast are slick, and though the humour is broad, there are some very funny lines delivered deadpan. ("How’s dad today?" "Green-ish.") But there are tonal shifts that don’t quite work. Fran’s seminar on home security is funny, but doesn’t seem in keeping with her personality, and at times it seems as if some elements of the show have been bolted on to show off a skill rather than serve the story.

It is never quite entirely clear why the patriarch has placed these ridiculous restrictions – whether it was just to keep them close, or specifically because they are girls. So the satire is better when it moves towards a wider point about society: that those most afraid of something are those that have never been in danger of anything, just as those that are most suspicious of immigrants and “outsiders” are often those that have least experience of them.

As the play progresses, what has started as akin to farce turns into something very different, and something quite special that has been built up in the sisters' relationship is lost. I’m not entirely convinced that the company have made all the right decisions during their development of this piece – but it shouldn’t be doubted that The Sisters of Castleknock House is funny, with quality ensemble playing and a surprising edge to its satire.