It’s a great week for powerful, thought-provoking drama in Oxford. The meaning of love (in About Love) and the impact of bereavement (in Moth) are both on display in stirring productions. Now Sap addresses the victimising of bisexuals in a play that reimagines Ovid’s Metamorphosis of Daphne in a modern-day environment.

Unlike those other two plays, Sap was not written by a current Oxford undergraduate. Rafaella Marcus was a Magdalen student fifteen years ago, and yet this is her debut play, first staged in 2022. Why it took her so long to put pen to paper I have no idea, as Sap is a bold, virtuoso piece, brimming with passion and purpose. Its theme is the exclusion of bisexuals from the LGBT+ community, in this case specifically the prejudice encountered by a bi woman from her lesbian partner (and her treatment at the hands of that partner's brother).

The remarkable – and I mean phenomenal – thing about Sap, though, is the demand it puts on its central character Daphne, played by Siena Jackson-Wolfe. Virtually the entire play (sixty minutes) is a monologue by her. It’s punctuated by conversations with other characters (all played by one actor, the impressively shape-shifting Luke Bannister), but even those scenes have an underscore of annotation from Daphne that runs throughout the dialogue, somewhere between stream of consciousness and Fleabag-esque self-commentary. Jackson-Wolfe is not only word-perfect, but also gives everything to this role. She takes us into her confidence, shares her pain, her joy and her moments of horrific abuse with us, and she does so while somehow maintaining a detached eye on her own experience. In moments of Ovidian metaphor she switches into poetic descriptions of her own arborial transformation, and in moments of sexual abuse her despair and pain are laid movingly bare. Credit must go not only to both the actors here, but to director Rosie Morgan-Males who has somehow created an environment that gives them the freedom and confidence to explore experiences that are dark, profound and scarring.

Daphne’s growth, both as a person and as a metaphorical tree, translates convincingly from Ovid’s original to a modern milieu. In The Metamorphoses she was transformed into a Laurel tree in order to evade Apollo and his unwanted infatuation. But here, her vegetalisation (and if that’s not a word already it is now) is as much an imprisonment as it is an escape. The paralysis brought on by being caught in a situation of sexual coercion over which you have no control is convincing and upsetting to witness. And, as the programme makes clear, ‘sap’ has two contradictory meanings: it is both the lifeblood of a tree and the gradual weakening of one’s own will. Both are present here. Jackson-Wolfe’s permanence on the stage has the fixed nature of a tree, while Bannister flits around her, a hummingbird poking and stealing the goodness from her limbs.

The only element that acts as a bit of an anchor, surprisingly, is Marcus’s script itself. Compared to the untrammelled, imaginative freedom of some of the new student writing in Oxford at the moment, this feels, for a play about metaphorical trees, slightly stuck in its roots: having had its big Ovidian crossover idea, it then follows the concept through and becomes a bit predictable, like painting by numbers. And there is a moment towards the end when Daphne becomes a statistics newsreader, giving us the data about how many bisexual people are abused by their partners, which feels like it’s piledriving the message home with unnecessary bluntness, like the ‘science bit’ in a shampoo commercial. A little more lightness of touch on the author’s part would have been welcome – and would have suited the subtlety and artistry of this production.

That artistry extends to the technical side of Sap as well as the acting and directing. Behind all the complex but enthralling action is a sound design from Joshua Robey that effectively acts as substitute for any physical set. In fact the only thing on the stage is a tarpaulin across the back, giving a sense of blanket anonymity to the action. As the scenes flow in Daphne’s memory, from street to nightclub, and from busy workplace to imagined forest, the sound fills in the details for us, a background cacophony of sirens, bird-calls, conversation and musical beat. In short, it feels as though everybody involved with this production is working at the top of their game. It’s been quite a week.