The first fiction feature from director Alice Diop, who has previously worked in documentary (her films include the multi-award-winning We), the French-language courtroom drama Saint Omer is as intriguing as it is intellectually rigorous. Inspired by Diop’s own experience of attending the trial of a woman accused of murdering her baby, it’s a meditative exploration of a complicated connection between the woman in the dock and the one who bears witness.

Rama (Kayije Kagame), Diop’s alter ego in the story, is a writer looking for inspiration. She is also pregnant and processing a tangle of emotions about what it is to be a mother. Laurence (the remarkable Guslagie Malanda), a charismatic and eloquent Senegalese immigrant, is serenely assured as a defendant in the murder trial, but jarringly discordant when it comes to her experiences of motherhood. Diop deftly depicts the two women as distorted mirror images of each other: Rama recognises something in Laurence even as she abhors her crime.

• Saint Omer is in cinemas in the UK now and from 7 March in Australia