If you hadn't picked it up from the 1960's music, a glimpse at the impressive period set would instantly anchor this play in time. A lesser-known script by Joe Orton, The Ruffian On The Stair belongs to an age when a man was the king of his castle – even if the castle's a bedsit, and the king is barely scraping through. The ruffian of the title comes later; we first meet the bristle-moustached, square-shouldered Mike, a middle-aged ex-boxer who's kept tolerably in shape, the very image of self-conscious masculinity.

The ambiguous relationship between Mike and his partner Joyce forms the backbone of this play, and actors Pádraig Lynch and Kiki Kendrick eloquently capture its constantly-shifting tone. There's misogyny there, certainly, and occasionally genuine cruelty… but underneath it all, there's unmistakeable love. We learn soon enough that they both have chequered pasts; somehow they've found each other, and somehow learned to give each other what they both need. We witness shifts of mood between them, but not of fundamental temperament.

Yet when the eponymous ruffian finally appears on the stair, that supportive relationship begins to fall apart. Joyce knows from the outset that he's up to no good; but Mike doesn't believe her, and soon she finds herself both terrorised and marginalised inside her own home. The manipulation is painful to watch, and Elliot Rogers is deliciously two-faced as the unwelcome visitor, charming his way into Mike's affections with an appeal to a half-imagined past. The mix of vulnerability and malice is delicately portrayed, and it's hard not to wince at the ruffian's uncanny ability to prod both Joyce and Mike exactly where it hurts.

The tension's well-punctuated by moments of humour – and there are a couple of genuine acting highlights, as all the characters come ever closer to lurching off the rails. Often though, the script's origins as a radio play are all too apparent, for example in an extended scene where Joyce describes to nobody in particular a series of events we can perfectly well see going on. At times too, the intentionally over-wrought style risks overpowering the storyline, losing some of the genuine horror inherent in the situation and developing plot.

So this isn't quite a lost classic by Joe Orton; the concepts and characters don't resonate as strongly as they might do, and the strange, jokey ending feels somehow incomplete. But even a not-classic Orton is well worth seeing – and this is a stylish, finely-tempered, enjoyable production. I laughed and sometimes flinched at what these mixed-up people did to each other, and by the end I genuinely cared about all of them.