In James Rushbrooke's play, a twelve year old girl is in isolation, surrounded by one-way mirrors and observed by psychologists 24 hours a day. Jessie, superbly played by onetime Matilda Eleanor Worthington-Cox, is a specimen, and a rare one at that: one of the last remaining psychopaths on the planet. Her mother slipped through the in utero screening process that has wiped out a number of genetic disorders entirely, Down's Syndrome being the latest.
Pyschopathy is a curious one though. Being a latent condition, the psychopath gene might not manifest in psychopathic behaviour. Charlie (Edward Harrison) is the doctor tasked with confirming if Jessie is a danger to society or not, after his kindly predecessor (silky-voiced Diana Kent) failed to find conclusive proof. Doing so means pushing the patient towards violence, enflaming her temper to see if she lashes out.
Rushbrooke's debut, winner of this year's Papatango Prize, is manna to moralists: a chewy mix of medical ethics. Does the eradication of certain conditions justify society's eugenics? Jessie is an extremely talented artist, drawing her care nurse Tom (Brian Doherty) with remarkable accuracy. Why should one negative genetic trait overrule all others? Elsewhere, other goods conflict: the duty of care against the duty to ensure society's safety, the need to manipulate Jessie to allow her freedom later on.
Those tests give the drama its zing. Once or twice, it conjures real danger. Jessie wields a colouring pencil like a dagger. She's restrained, her oxygen cut off in a choke-hold – an alarming thing to watch. Her inscrutability ups the tension: as she runs her fingers over Tom's face, oh so gently, we brace for the moment her thumbs plunge into his eye sockets.
However, teasing ethical complexity doesn't recompense for the lack of human interest. Despite Rushbrooke's attempt to give Charlie a private life – his partner at home is waiting for the results of her own scan – his characters are basically pieces in an ethical dilemma: doctor, doctor, patient, nurse. They don't really have stories of their own.
Doherty makes the most of that, turning Tom into an enigma. This ex-military man, gently plaiting his young patient's hair, is a poker-faced pro. It's a gorgeous performance: an affectionate surrogate forced to remain detached. Worthington-Cox is equally complex and unreadable, attuned to odd behavioural tics that raise the nature-nurture question. Growing up in lab conditions would turn any of us psychopathic, and Kate Hewitt's finessed direction is aware of the paradox of experimentation: how do you test for abnormality in abnormal conditions?
There are shades of Blue/Orange in Rushbrooke's writing, though he can't match Joe Penhall for poetry and purity. Nonetheless, he sidles up to this futuristic – though far from far-fetched – society with impeccable control, drip-feeding us the information we need. His characters live in this world. They don't lay out its rules for our benefit.
Scrape off the sci-fi surface, however, and Tomcat's really concerned with civil liberties. In a way, we're all in Jessie's observation chamber, monitored by CCTV and GCHQ for anything abnormal. Scanning for and eradicating genetic disorders is not a million miles from our own surveillance state, and in particular William Hague's defence that only those with something to hide need fear such scrutiny.
Tomcat runs at the Southwark Playhouse until 21st November.