There's a skull sitting on the bookcase. Nobody ever mentions it, it has no role in the plot, but you can never quite forget that it's there. And that, to me, exemplifies the quiet menace of this well-thought-out horror story, which takes the most time-worn of elements – a haunted house, a dinner party, a séance gone wrong – and still manages to combine them into something intriguing and new.

Be warned though: it's very slow to get started. The set-up is methodical, almost formulaic, as characters arrive one-by-one and embark on lengthy expository dialogues with each other. There's really no need for this; the broad-brush personalities are easy to get a handle on, and only one character – paranormal investigator Dr Earle – has a significant back-story to share. What we're left with is essentially an hour of pre-dinner chat, advancing the narrative at a crawling pace.

But hang in there: once you get past the laborious first half, something far more creative and intelligent emerges. Dr Earle's Chandleresque tough-guy persona conceals hidden emotional damage, and for a lot of the play there's a pleasing ambiguity about whether we're watching a ghost story or a psychological drama. As he clings onto his scepticism in the face of mounting evidence of the paranormal, actor Peter Slater masterfully portrays both outer stubbornness and inner decline.

The characters surrounding Earle range from semi-parody stereotypes to quietly threatening foils, and each plays their own part in cutting away the solid ground around him. Cleverly, some of the biggest chills are delivered by an understated character, with playwright Joe O'Byrne himself filling the role of the butler. Jo Haydock plays the only woman of the piece – a thoroughly modern journalist who might just be Earle's equal – and does a good job of linking the plot together and moving the action on.

The ultimate twist to Earle's story is startling but believable, and a few hints seeded early on are carefully harvested at the end of the play. Justin Wetherill's sound design deserves a mention too: it's disturbing and unsettling, without relying on the cheap trick of jump scares. In fact, the fright level is well-pitched overall – nerve-jangling, but not unpleasant or overwhelming, relying more on uncertainty and menace than on shock.

It's a shame that the intricate conclusion is stuck behind such a plodding opening, but there's a great deal here to appreciate and enjoy. I loved the nods to horror tropes, the powerful sense of place, even the lavish period set. Overall, I can recommend a visit to Blaine Manor – and keep your wits about you. The truth is surprising… yet just like that skull, you'll realise it was staring you in the face.