A true story about a gender-nonconforming couple in 18th-century Germany has been rescued from history by playwright Ruby Thomas. The source material – predictably, records of a trial – is scant but has served as the inspiration for a fulsome and rewarding script.

Anastasius Linck was born female but lived as a man and had a military career before marriage to Catharina Mülhahn in 1720. The subsequent trial of both offered Thomas what must have been tempting opportunities (Linck spent time as a prophet!) that have been condensed to present a focused show with epic qualities of romance and history.

If it crosses your mind that Linck & Mülhahn sounds sentimental or worthy, the sparkling script corrects this quickly. There is a wicked balance of old and new idioms that is a delight. Some of the metaphors are heavy, but plenty have charm. And the dialogue is fun!

The serious subject and often playful tone make great titular roles for Maggie Bain and Helena Wilson, who are both excellent. There’s a strong part, too, for Mülhahn’s mother, where Lucy Black gets to show off comedy skills before revealing her character’s spite and becoming an interesting villain.

Director Owen Horsley gives us romance but stops the lovers becoming too sweet by emphasising their wit. It’s a shame that contemporary music breaks up the scenes – it feels a lazy way to make the show feel modern – but Simon Wells’ deceptively simple set is highly effective.

There are a lot of philosophers mentioned in the play (although, interestingly, not Kierkegaard, who I suspect is closest to Thomas’ heart), which is an easy way to get big questions aired. All the talk of “essences” might be explored more. And the intellectual atmosphere of the age is evoked a little loudly. But the play’s attempts to respect history, avoiding modern labels for its protagonists, while making contemporary concerns clear and moving, is impressive. There’s an excellent sense of balance and directness throughout Linck & Mülhahn that shows intelligence.

It’s no plot spoiler to reveal that in real life the story ends sadly. So, getting the Queer Joy that’s topical (and so welcome that I’ve capitalised it) is hard. Fear not, as Thomas makes every effort and is aided by Marty Cruickshank, who plays Mülhahn’s older self. This is not a big role, but Cruickshank might just end up the star of the show – recounting the sheer bliss of her marriage provides the “light” the play is explicit about wanting.

The trial scene is uncomfortable but is tackled as an odd blend of humour and inspiration. Stock judges and lawyers – pompous, sharp or asleep – are there to be laughed at. We can applaud those who testify for Linck – and both concluding speeches. But the final cheers are for the writer, Thomas. The parting between the couple is wonderfully romantic and a fanciful touch that brings us into the present provides a heart-stopping ending.

Until 14 March 2023

www.hampsteadtheatre.com

Photos by Helen Murray