Political intrigue, 17th century religious dogmatism and a steamy Mexican powder keg: all the ingredients for Helen Edmundson’s new play for the Royal Shakespeare Company are ready to be brewed into a fascinating concoction.

And chef Nancy Meckler, directing this historical study of the Catholic Church’s oppression of the playwriting nun Sister Juana Ines de la Cruz, does so with panache and plenty of chilli-hot emotions.

She is ably assisted by Katrina Lindsay’s designs and Ben Ormerod’s lighting, both of which add to the sultry undertones and darkly luxuriant opulence of the Spanish overlords in Mexico City circa 1690.

But it’s the performances that really grip as the drama unfolds, painfully slowly to begin with, then gaining pace as the three hours roll out, to culminate in the inevitable but still achingly poignant destruction – both physically and mentally – of this extraordinary, vibrant woman with too much to say for her Archbishop’s liking.

Catherine McCormack shrugs off the constraints of her wimple to convey strength, vulnerability and deep self-doubt in a wide-ranging and highly engaging rendition of the nun herself.

Geoffrey Beevers vacillates and equivocates as her Father Confessor, more interested in which side his own bread is buttered than in protecting his protégé. And Stephen Boxer emanates menace in his still, but powerful, Archbishop.

However, it is Raymond Coulthard who clinches the ultimate success of the evening as Bishop Santa Cruz, whose very human emotions lead him first to exploit Juana for his own ends then to betray her cruelly and devastatingly. His utterly believable portrayal of the worldly man lurking beneath the sheen of his cassock is weighty and charismatic enough to carry any flaws of motivation in the writing.

For Edmundson’s play is, indeed, flawed. While it purveys majestic sentiments in high language and develops considerable pace by the shorter second act, it also suffers from some shallow characterisation and motives at vital points, while offering little in the way of hope or redemption for its central tragic figure. The villains, meanwhile – mostly men, it should be pointed out – suffer no retribution or even remorse, undermining what could have been a powerful message and rendering the outcome simply rather bleak.

That is not to say there isn’t a great deal to recommend the production, and the RSC’s continued devotion to challenging and interesting new work is, of course, to be cherished. Coming on the heels of David Edgar’s equally intriguing Written on the Heart, The Heresy of Love makes a welcome companion piece.

- Michael Davies