Vermin. Park Theatre.

First seen at the Edinburgh Fringe in 2022, Benny Ainsworth’s mordant modern gothic horror story Vermin had a well-received 2024 run at the Arcola Theatre, where it garnered an Offie nomination for Best New Play and a win for Sally Paffett in the Best Lead Performance category. Director Michael Parker’s revival at the Park Theatre will not suit some tastes: elements of the piece are decidedly gruesome, and you may find yourself squirming in your seat at the more explicit descriptions of violence. But, amidst the grotesque imagery and pitch-dark humour, Ainsworth’s piece has something important to say about the draining destructiveness of unresolved grief.

Thirty-something Billy (Ainsworth performs as well as writes) has OCD, intrusive thoughts of murder, and proudly confesses, “When I was a kid, I liked killing stuff,” by which he means cats, birds, and insects. On a commuter train to Victoria, he bumps into the flirty and gregarious Rachel (Sally Paffett is absolutely tremendous). The duo bond over an immediate sexual attraction (“I sniffed her hair, fruity!” Billy tells us) and a fascination with the mechanics of the suicide on the tracks in front of the train (“a sad puff of candy floss guts”). Three months later, they are an item, and a month after that, they marry. They make for a cutesy pair of psychopaths. She is proud and slightly in awe of him. He finishes her sentences. Think a chatty, working-class Streatham version of Bonnie and Clyde or Natural Born Killers.

The loved-up couple moves into a cosy flat, but there is an issue. The place is infested with rats, which are multiplying quickly beneath the floorboards and between the walls. Bloodthirsty Billy wants to get rid of them as violently as possible. Rachel, however, finds herself completely enamoured with the vermin and soon transforms into a mash-up of Dr Dolittle and Pied Piper of Peckham. Anticipate twists, turns and a gory conclusion as the couple battle their differences out with, variously, an air rifle, a hammer, and poison.

Second-act revelations hint that the vermin infestation is a metaphor for unresolved anguish at an awful tragedy that has struck the couple (powerfully rendered in an intensely painful scene from Paffett). The point being that, however hard we try to bury unprocessed grief, sooner or later it will gnaw its nasty way to the surface. Director Michael Parker keeps the momentum flowing, and the edgy bickering chemistry between the protagonists impresses.

Writer:   Benny Ainsworth

Director:    Michael Parker