If the initial phone call from Scream lasted an entire film, the result would be something like this halfway-decent B-movie thriller. Jessica Morris stars as the presenter of Sarah Cares, a call-in radio show/podcast in which she solves listeners’ emotional dilemmas, often in tough-love, no-nonsense fashion. On the verge of signing a big-time New York contract, her week goes awry when her studio falls victim to a bomb scare. Then on the following day her phone lines are blockaded by Edward, an aggrieved and apparently abusive husband; Sarah had previously told his wife to ditch him.

Edward says that all he wants is moral consistency. Sarah, the supposed font of all wisdom, is living in a sham marriage and he has the proof locked up in his shed: her husband’s new lover Alice (Carly Diamond Stone). Unless Sarah wants Alice’s death on her conscience, she has to abide by two rules: no cops, and complete honesty when Edward asks a question. After the insipid setup involving Sarah’s radio colleagues, and then the hypocrisies of her home life with husband David (Adam Huss) and daughter Maya (Aliza Kate Barlow), Killer on the Air becomes increasingly compelling the more minimalist it gets; a duel between the unravelling DJ and the malevolent green waveform on her screen.

As Edward strips Sarah down to her childhood trauma live on air, Morris nails the theatrical bedside manner, and how she surrenders to true candidness (“I think they call that a breakthrough!” gloats her tormentor). The backstory also nicely handles how her empathetic yet judgmental therapeutic style flows from her parents. Outside the studio, the accompanying runaround – as David and a hunky detective (Andrew Fultz) try to hunt down Edward – and the final twist feel a bit obligatory, and Haylie Duff’s direction is a tad pedestrian. All the same, her film circles intriguingly around the podcast age’s performative emotions and authenticity fetish.

• Killer on the Air is on digital platforms from 18 May.