NORTH West company Postcard Theatre have crossed the Pennine border line for the first time to stage a show in York.

Playwright Ruby Clarke, former artistic director of York Theatre Royal's TakeOver festival and now directing York Shakespeare Project's Timon Of Athens, knows Postcard director John-Mark Reid from their St Martin's College student days in Lancashire, hence this week's two performances at the Friargate Theatre.

Preston's Postcard are in their first year, Border Line is their third work in that time, and it is the kind of concise, compact theatre – 70 minutes in duration – that has the Edinburgh Fringe running through its core.

Normally you wouldn't trust a play with so much tea-drinking, the (off-stage) boiling of kettles and sipping of tea being the ground zero of early play-writing when seeking to inject movement, entries and exits into a script, but Oscar Wilde made it work in The Importance Of Being Earnest and Ruby Clarke knows how to make a good cuppa scene or two in Border Line.

Averse to confrontation, teacher Claire (Jenny Owen) has moved into a new flat after hastily leaving her previous school to escape an uncomfortable relationship. Another one is brewing, however, because she has been befriended by Stella (Julia Walsh), who not only invites herself in but brings her own tea leaves that she duly strains through a cloth. Obviously an oddball, right? Yes, but where does the border line blur between over-concerned oddball and stalker, a "grey area" that pushes Claire beyond her "predicament of politeness", beyond police inertia, beyond a once-tight, now fraying friendship with Jackie (Amey Woodhall)?

Full of questions and mind games, Clarke's taut, darkly humorous, unsettling sitting-room drama combines intrigue and social politics with a twisted gothic finale worthy of Saki, rendered convincingly by a cast walking a tightrope between the fearful and the fanciful.