The Corpus Playroom is literally the perfect setting for Jez Butterworth’s difficult second play. Literally. We sit just a rather fatigued arm’s stone’s throw away from the gardens of Corpus Christi College, whence the two protagonists of our story, as former gardeners there, have been banished, accused of a crime that looms in the shadows, and which keeps them at arm’s length from their garden of innocence. We too, then, join them here in their poky exile, dark and dank and cold as a barn out in the Fens will be at this time of year. A sense of the bleakness and foreboding of the marshes hangs over us, inexorable, curdling the air, as we dive into a psychological landscape of hounding fear, rural belonging and religious passion.

Indeed, the atmosphere is one of the best-handled aspects of The Night Heron, aided in no small part by the tiny Corpus Playroom’s inherent intimacy, and so tribute must be paid to the excellent sound and lighting team for their part. But the actors’ performances, on which the play really depends, were alluring enough to sustain this sense of claustrophobia. First year Jamie Robson’s Jess Wattmore is a suicidal religious fanatic, with one foot in a strange spiritual cult, who accuses a boy scout of possession by the devil – but where one might expect a raving simpleton, Robson’s portrayal is far from that, and feels more mature than that; he lends a tenderness to the role, a beautiful sincerity to this tortured figure. Fellow ex-gardener Griffin, who becomes fixated by a £2,000 Cambridge University poetry competition as a way out of their exile, is somewhat wobblier played by a slightly uncertain Nick Ash. Perhaps with a little more conviction, and a couple more rehearsals as an ensemble, the character will come together a little more compellingly. It certainly needs a strong hand.

The strongest of hands on the night, though, was undoubtedly the deadpan Carine Valarche in her first named role as gruff, blunt and truly menacing ex-convict Bolla, the boys’ lodger, reciting Marvell in a thick East London accent. She was assured, and had some of the most bizarrely hilarious lines of any play I’ve ever seen. But that is precisely what you can expect from Jez Butterworth: outstanding dialogue, punctuated by scenarios you couldn’t even dream up. Bolla tells us, for instance, of her mother’s days as a bedder at John’s, where she would clear used rubbers off the bedstead of each undergraduate while he was “busy off somewhere singing in Latin”. That, admittedly, you probably don’t have to dream up here. That Cambridge is at the core of this production makes it quite a self-aware, even unnerving experience; we feel part of the game, in part for it is we who will read all about it in the local press should our protagonists’ secret be splashed over the front pages.

Admittedly there was some awkward crowding onstage towards the close, and the whole thing should have been a lot slicker at times (I expect that the cast will work on this throughout the remainder of the run), while some of the acting could have reaped much reward from a little fine-tuning. The relationship between the two male leads, for example, left one rather empty; one felt that they should have been at home in the ‘old married couple’ schema, but they just didn’t seem to fit together as a pair. What is more, both were both guilty of unconvincing physical acting at one point or another, their movement at times lacking the finesse of Robson’s handling of his verbal lines: nooses were thrown haphazardly away in a fashion ill-befitting one who wishes to hide from his nearest and dearest how unhappy he is; Griffin’s mannerisms needed to be definite, and moreover refined, but it too often felt as though both Ash and Robson were forcing the cues laid down in the text. And while we’re at it, there are few moments on stage more reminiscent of an amateur production than pointedly failing to pour actual liquid when characters grab glasses for a drink, and this was out in force during the performance I saw, which, if you noticed it, lowered the whole tone of the play, and reminded you that you were sitting in a theatre – the very last thing writer, director or actor desires.

Whilst these are all problems, however, the wit of the script, comic and tragicomic, oozes through the gaps and sticks it all together as a congealed mess, saturated with deafening Biblical imagery and heavy under the weight of the skeletons around which the narrative unfolds. The second half is a slight let-down on the first, it is true, though, again, we are treated to such a feast of moods that to be lulled in any sense is never likely. Indeed, tones that transport us from apocalypse to absurdist melodrama in the flash of a wingtip render the question ‘what is this play about?’ rather redundant. The answer would probably involve Religion, Patriotism, Taboo, Sex, Death and most other words you can think of to add a (moderately pretentious) capital letter to, but these all spin like tiny planets in orbit around their central star, rather than clinging limpet-like to it. It means that Butterworth can prod at some very big questions, but perhaps never with the sincere intention of giving us any meaningful answers. Perhaps he is pointing to us, each of us, as players on the stages of one anothers’ lives, or perhaps not. What is clear is that he asks us to think very carefully about the significance of our own paradisal gardens, both the pretty ones on our little doorsteps in our little colleges, and the rather bigger (and perhaps scarier) ones inside our heads; so I invite you to go and see The Night Heron.

Even if you don’t discover what lurks in your own garden of earthly delights, at least you’ll have a stonking good time at the theatre, your stereotypes about inbred fen-dwelling religious nutters in the rural surrounds of Cambridge town firmly intact.