You’ll need your wits about you, and at times you’ll feel you’re barely clinging on to comprehension.
But stick with it. The Caller is a genuinely chilling treat, intriguing and ultimately satisfying - a novel new twist on the old phone pest saga.
When troubled divorcee Mary Kee (Rachelle Lefevre) moves into her new and gloomy apartment, it’s not long before she starts getting persistent, weird phone calls.
The double whammy is that Rose, her caller, is not only a nutcase; she’s also phoning from 30 years ago.
Mary is initially sympathetic and seemingly dissuades the disembodied voice from hanging herself - a grave mistake: for by altering the past, Mary sets up wide-reaching ramifications in the present.
Not the least of her problems is that by saving the elderly psycho’s life, Mary frees Rose to kill everyone around her - people who suddenly start disappearing from her present.
Even worse is the fact that Rose is now free to capture and torture the child that Mary once was...
You’ll get a headache just thinking about it, but somehow it all seems to hang to together as it hurtles towards a gripping finale. Reach the end and you’ll probably want to go right back to the beginning to see just how much it makes sense - but the impression is that it does.
Lefevre is excellent as the poor girl at the centre of it all, and director Matthew Parkhill is excellent at teasing out the shudders in a film more than half of which is spent on the phone.
Make sure you catch the DVD extras too - fascinating to see how the story, in search of producers, moved from Glasgow to New York before finding its natural home in Puerto Rico.