As a subject, religious fanaticism – particularly of the cultish variety – can not be an easy one to write about whilst retaining a sense of honesty, realism and balance. In Haunted Child, Joe Penhall does a decent job of fleshing out the arguments for and against surrendering the daily, humdrum cycle of modern existence for a ‘scholarly life’ with added saltwater-based rituals, but often forgets the presence of an audience.

His premise is strong: the return of a missing father throwing his family into crisis with a collection of esoteric philosophies, a shaggy beard and a need to renounce all worldly ties works well as a baseline from which to explore the conflict between society and the individual, faith and expectation. Which makes it all the more frustrating that the first act is so bloated with exposition – from the opening scene which establishes Julie as a mollycoddling mother with an aversion to organised religion through to the lengthy monologue in which Douglas gives a no-holds-barred account of his time away, one wishes that Penhall had explored the shadowy ambiguities of his plot rather than focusing on the back-and-forth discussion.

The piece picks up post-interval mainly because Ben Daniels’ performance moves from strength to strength. Tentative direction from Jeremy Herrin may threaten to turn Douglas’ bizarre convictions into the stuff of spoof, but Daniels performs with such fidgety, compelling sincerity that he manages to ground his character’s oddities in the realms of believability. Okonedo handles confrontation scenes well, with a conflicting mixture of pity, anger and disbelief, but is far less successful in scenes with Jack Boulter as her son, Thomas. Where Julie’s words suggest care and soothing, Okonedo gives us patronising shrewishness, and scenes which call for her to be playful simply don’t ring true.

Perhaps a strained mother-son attachment is intended to highlight the latent similarities between Thomas and his father; certainly Herrin doesn’t pass up on the opportunity to turn this suggestion – one of Penhall’s subtler ones – into bare-faced, obvious certainty in the final scene. This is just another example of where this production feels strangely muddled; sometimes too understated, at others teeth-grindingly heavy-handed. What does seem clear is that the line between unsettling and awkward has been misjudged, leaving one feeling that – though certainly watchable in its current state – Haunted Child needed a stronger sense of artistic intention from both playwright and director to fuse its intelligent debate with an appropriate sense of drama.

Haunted Child is playing at the Royal Court Theatre until 14 January. For more information and tickets see the Royal Court website here.