What a surprise. Snake in the Grass is an unknown 90-minute ghost story and thriller by Alan Ayckbourn dating from 2002, not before seen in London. It suits the tiny new Print Room off Westbourne Grove perfectly, or at least in Lucy Bailey’s highly charged, atmospheric production, it does.

Two middle-aged sisters, divided for many years, come together on a crumbling outdoor tennis court in the family house after the death of their father. Miriam (Sarah Woodward), bitter and spinsterish, has been doing the dirty work of looking after the abusive old boy while Annabel (Susan Wooldridge, a failed businesswoman), has been abroad in Tasmania.

There are twists and turns right to the end, but the dominant situation is that Miriam admits that she over-dosed Dad and pushed him down the stairs, and that his former nurse, Alice (Mossie Smith), an abrasive loudmouth bearing a grudge, knows the score and wants a big pay day in exchange for keeping clear of the police.

Beyond revealing that Miriam is more cunning than she seems and that Annabel has a heart condition, it won’t hurt to say there’s a deep, disused well in the garden that comes in handy, a dodgy electrical set-up, some nifty bottle-switching and a creepy soundtrack of bats, birds and distant cries.

Wooldridge and Woodward expertly play the minefield of resentment and sibling rivalry that everyone will recognise when it comes to these ageing parent-related domestic matters, and their central passages of dialogue are fraught with painful detail and acid pay-back.

But the passage of time has hardened one more than the other, and this drives the plotting to its eerie conclusion. The acting is superb, Woodward’s chill authority and Wooldridge’s slipping grandeur making them distant cousins of the old crones in Arsenic and Old Lace. William Dudley supplies one of the best realistic cramped settings you’ll ever see: a dilapidated court with scuffed tarmac, a chicken-wire fence, a crumpled net and an old green umpire’s chair that has strangely retained its authority to rule on dubious decisions at the back of the court. The atmosphere’s reinforced, too, by Richard Howell’s excellent lighting for afternoon and night-time. Creepy.