The title’s drawn from a Biblical verse, but the story is diabolical. Locusts centres on Stephen, a gay man well into middle age, who’s happily engaged to his partner Jeff and seems to be surrounded by supportive friends. But there’s a shadow in his past, a terrible wrong he once suffered from a man he both trusted and revered. And now, like a spectre, that figure’s returned – with no conception of the wickedness of what he has done.

Ian Tucker-Bell and Garth McLean’s script is delicately crafted, setting up questions and holding back answers, capturing our interest from beginning to end. But it isn’t a spoiler to reveal the main theme: so-called “conversion therapy”, the misguided belief that people like Stephen can be “cured” of their sexual orientation, either through pseudo-science or by an intervention from God. As a young man, Stephen belonged to an evangelical church, and came to believe his growing sexual feelings were a terrible sin. We learn what happened next – and the hidden harm it’s done to Stephen – as he confronts his memories, with the tender support of his partner and his friends.

Tucker-Bell appears as Stephen, and his performance is outstanding: understated, nuanced, and profoundly touching. When he’s in his former pastor’s presence, even after all these years, we witness a sudden loss of confidence – see remembered shame in his downcast eyes. Playing the pastor, Nick Blessley projects a kind of banal malevolence, charismatic but unremarkable at the same time. Yet we’re invited, if not to sympathise, at least to understand him; the rigid beliefs that once ensnared Stephen have him in their clutches, too.

Stephen’s partner Jeff (Pierse Stevens) has a poignant and important story as well, a family hurt that’s cast its own long shadow, born not from hostility or outright rejection but simply a refusal to engage with the truth. Completing the cast is Julie Flower as Sian, who speaks for the audience in her simple incredulity at what Stephen gradually reveals. And it’s all brought together by Phil Holden’s direction, which lends the staging quiet dynamism while keeping the storytelling crisp and clear.

What Locusts explains – so powerfully and so vitally – is that “conversion therapy” is a torture that works from within. Stephen was once a child of faith, a true believer not just in God’s grace but in the authority of religious leaders on Earth. So when his pastor promised that God would “cure” him, and when God did not deliver on that guarantee… we can only imagine how desolate and forsaken that made him feel. This talented company have gifted us the very best kind of activist theatre: the type that doesn’t shout its message, but reveals, informs, and guides us back into the light.