Following up his promising debut Just Jim, Welsh director Craig Roberts (perhaps best known for his work as an actor in films like Submarine and Bad Neighbours) builds on that potential with a striking sophomore film that delves daringly into mental illness with wit and subversion. We're immersed in the experience of a paranoid schizophrenic, hanging onto reality by the slimmest of threads.

Our protagonist is Jane (Sally Hawkins), although heavily medicated when we meet her, we see how she is an anarchic force in the lives of her bewildered family – mum Vivian (Penelope Wilton), dad Dennis (Robert Pugh) and sisters Nicola (Billie Piper) and Alice (Alice Lowe). The film flashes back to the tragedy of Jane being jilted at the altar (Morfydd Clark plays the younger Jane in a turn that pairs interestingly with her barnstorming work in Saint Maud), an event that has haunted her, and there's a potentially troubling romance with David Thewlis's terrible musician and conspiracy theorist Mike.

Story-wise, there's not a huge amount going on here, but the film soars in its consistently imaginative take on the way Jane views the world and the sense of solidarity it fosters. Inventively shot, designed and staged, it unfolds in a pastel horror show of suburbia and deliberately mixes period influences and location details (the accents are mainly estuary but there's mention of the South Valleys); with time and place heading out of the window, it leaves us as disorientated as our protagonist.

Showing how the level of medication it takes to keep Jane 'sane' only serves to dull and diminish her existence, Roberts also posits that normality is nothing to aspire to in his cynical portrayal of her more conventional family members; Piper's sour-faced glamour-puss sister is particularly good and if you've ever wanted to hear Wilton call someone a 'fuckhead' then you're in luck. But the film belongs to Hawkins, who ensures that the comedic edge doesn't deflect compassion away from her character. She brings complexity and pathos to her portrayal of someone who is struggling to make sense of it all and fighting back against attempts to subdue her, resulting in an enjoyably atypical heroine.

Available to watch in cinemas and on demand from Fri 2 Oct.