The history of cinema is littered with mythical beasts – dragons, vampires, werewolves, giants and mummies. Ray Winstone doesn’t quite get included on the list as although his beast was of the sexy variety it wasn’t very mythical.

A beast that rarely appears is the humble unicorn; it has probably been most prominent in recent years in animated form in the My Little Pony films, as well as in origami form in Blade Runner, with a few glimpsing appearances in other films over the years.

This then sees the horned beast front and centre in this A24 film.

Driving to a retreat with his daughter Ridley (Jenna Ortega) is lawyer Elliot (Paul Rudd). They’re to spend the weekend with his wealthy ailing boss Odell (Richard E. Grant), his wife Belinda (Téa Leoni) and son Shepard (Will Poulter), with the hope of improving his position in the company.

But on the way Elliot gets distracted and hits something. From the car it looks like a small horse, but it’s only on closer inspection that they discover it’s none other than a unicorn. Ridley manages to touch its horn – and get a vision from it – just before her dad puts the creature out of its misery.

Although shaken, they continue on to the retreat. It’s there that Ridley realises that not only does she have unicorn blood on her face, but her acne has also miraculously cleared up.

Soon after they realise that perhaps the unicorn isn’t as dead as first thought, which Odell sees as a possible business opportunity as they feel its blood has healing properties.

But when Ridley does some research, she believes that they really shouldn’t be messing with this mythical creature, and she’s soon proved right.

This directorial debut from Alex Scharfman, which he also wrote, is a mix of black comedy and horror – but an uneven mix at that.

It’s a film where he attempts to strike a balance throughout, whereby you have an ignorant, arrogant family, with more money than sense, facing this violent mythical beast. And that’s part of the problem; as much as he tries, Scharfman simply can’t make these beasts believable killing machines – they’re cute unicorns after all.

He gives it a good go, trying to add elements from the likes of Jurassic Park and Alien to give it the necessary horror edge, but ultimately you can’t help but see the unicorns as horses with horns.

He does better with his script, and some nice amusing dialogue, as well as likeable performances from all his cast - who are clearly up for it, but there’s no getting over the obstacle that is the main premise, feeling like it’s literally flogging a dead unicorn.

It just feels like Scharfman used the wrong mythical beast, and that perhaps he may have been better off going with Ray Winstone after all.