Dan Stevens rips his cosy Downton Abbey image to shreds with a mesmerising performance as a cold-blooded killer.

He comes to stay with a grieving New Mexico family in this slick, suspenseful, explosively exciting and darkly comic psycho thriller.

Declaring himself a comrade of their dead soldier son, he seems the perfect guest. Yet, as his secrets slowly emerge, the neighbourhood’s body count rises…

This is a hugely enjoyable throwback to 1980s-style horror thrillers, with a heavily signposted Halloween setting, a doomy synth-laden score and even a deliriously over-the-top climax in a fun-house hall of mirrors.

But the film’s ace is undoubtedly Stevens, American accent and sinister smirk perfectly in place and deploying dangerous blue-eyed cool to lethal effect.