Writer Ruby Thomas was in the British Library when she came across a reference Linck and Mulhahn, a same-sex couple in 18th Century Prussia who'd been living as husband and wife.
Using what information she could find as starting point and imagining the rest, Thomas has written a witty, effervescent and heartbreaking play about their relationship, secret life and the subsequent outing.
It starts with Linck (Maggie Bain) living as a man - Anastasius - so they can be a soldier and Catharina Mulhahn (Helena Wilson) fighting her mother's attempts to match her with a suitable husband.
Anastasius is a skilled soldier and well-respected. Catharina is rebellious, constantly pushing against the boundaries society places on her sex. A chance encounter at a dressmakers shop sees the two verbally sparring; they fizzle and spark in each other's company.
There is an honesty in their biting, yet playful, exchanges that ignites something. When Catharina, with typical forwardness, proposes marriage Anastasius has to reveal that they aren't all they seem.
But Catharina is undeterred, and the two marry and set up a home together. Anastasius, who has now left the army, works as a dressmaker's apprentice and encourages Catharina to write.
It is a blissful existence built on a foundation of love and equality until Catharina's bored mother starts to dig into her 'son'-in-law's past.
Linck & Mulhahn is staged fairly simply. On a revolve are two white panelled walls with a corridor in between, and on one side is a white staircase. The set revolves to reveal new locations denoted by a few pieces of furniture and props.
Contemporary pop and rock tunes blast out, their lyrics appropriate, sometimes ironic. The way Anastasius and Catharina live as their true selves, albeit discreetly, also feels modern despite the period costumes.
And that is the irony that transgender and queer identities are viewed by some as a 'modern affectation' when the reality is that they've just been hidden from an unaccepting society.
Towards the end, a judge comments that without rules, there is no truth. However, the rules followed are based on the perceptions of those who make them rather than a universal truth.
The first half of the play is effervescent, with a tone as joyous as the freedom Anastasius and Catherina feel in their marriage. There are bubbles of laughter throughout, particularly in Catharina's gender stereotype-busting backchat.
As the second half unfolds, the often farcical court scene leads to heartbreaking tragedy.
I laughed, I grinned, and I cried while watching Linck & Mulhahn; I'm giving it ⭐️⭐️⭐️⭐️⭐️.
Linck & Mulhahn, Hampstead Theatre
Written by Ruby Thomas
Directed by Owen Horsley
Running time: 2 hours and 25 minutes, including an interval.
Booking until 4 March; for more information and tickets, visit Hampstead Theatre's website
Phaedra, National Theatre ⭐️⭐️ for the staging ⭐️⭐️⭐️⭐️⭐️ for the play and performances.
The Elephant Song, Park Theatre ⭐️⭐️⭐️⭐️ booking until 11 February.
A Streetcar Named Desire, Almeida Theatre ⭐️⭐️⭐️⭐️ and a half, booking until 4 February (This production will transfer to the West End on 20 March).
Orlando, Garrick Theatre ⭐️⭐️⭐️⭐️ booking until 25 February.