With 2014’s The Canal, writer and director Ivan Kavanagh demonstrated an aptitude for psychological horror. Son feels like a natural progression, adapting a Rosemary’s Baby influenced storyline to show what might have happened had Rosemary escaped the devil worshippers and fled with her child. Oh, and there’s more blood. An awful lot more blood.

In a seemingly idyllic suburbia, Laura (the excellent Andi Matichak) is raising her son David (Luke David Blumm) alone. But when he begins to exhibit signs of a mystery illness it seems Laura’s hidden past has finally caught up with her.

Cults are scary, let’s all agree on that. And especially ones built on a belief in the imminent arrival of a devil-child. So, when Laura suspects that the one she escaped from as a teenager has returned to claim her son you can understand her concern. Only, was the cult real or is she, according to her former psychiatrist, simply making it up to distract from her own crimes?

Kavanagh’s themes of questionable reality, coupled with a seemingly unreliable narrator give Son an unsettling, rather untrustworthy atmosphere, leading to a finale that may prove divisive depending upon your position. This may be a well-trodden path for horror movies, but Kavanagh expertly crafts his tale, allowing questions to linger, maintaining interest by casting enough doubt on what is real and what is fantasy.

And this is bold filmmaking; some of the imagery, and certain scenes, are unflinchingly brutal and gruesomely striking, repeatedly challenging the audience.

With Son Kavanagh has proven his filmmaking instincts are strong, drawn intense performances from a strong cast, and delivered a horror film worthy of the name.

Son is streaming on Shudder.