The trials of Liverpudlian comic John Bishop are the unlikely blueprint for Bradley Cooper’s third film as director (following A Star Is Born and Maestro). Set in New York but loosely based on Bishop’s belated entry into the stand-up world, the film follows Will Arnett’s Alex Novak, who, when we meet him, is employed in the financial sector and miserably married to former champion volleyball player Tess (Laura Dern). When the pair agree to split and share custody of their two young boys, Alex finds himself spiralling and inadvertently ends up on stage at an open mic night, where he pours out his troubles to the crowd.

Balls, Alex’s feckless and self-absorbed actor friend, is played by Cooper, with Christine Ebersole and Ciarán Hinds his hilariously well-meaning parents. Cooper co-wrote the screenplay with Arnett and Mark Chappell (See How They Run) and the trio really capture the destabilising, lonely and bewildering nature of separation, and how stand-up can act as therapy for those working out their issues. Tess might not be the film’s focus but she’s credibly drawn and beautifully brought to life by Dern.

Best known for his comedy, Arnett gives a hugely vulnerable and deeply felt performance, one that withstands the scrutiny of this unashamedly soul-searching and intimate (yet still very funny) film, fluidly shot by regular Cooper collaborator Matthew Libatique. There are a few very cinematic speeches but, on the whole, Is This Thing On? takes a refreshingly realistic approach to relationships. It’s such a charming, humane and wise film that even the outrageously on-the-nose musical choice that wraps things up is impossible to resist.

Is This Thing On? is shown at BFI London Film Festival, Sunday 19 October; in cinemas from Friday 30 January.