Sundown stars Tim Roth as a man behaving mysteriously

Mexican writer-director Michel Franco hasn't achieved as high an international profile as his countrymen Alfonso Cuaron (Gravity) and Alejandro G. Irritu (Birdman,The Unexpected Virtue of Ignorance). But he's been working steadily for years and, on the evidence of this film, he's another fine, if less flashy, talent.

Neil Bennett (Tim Roth, who worked with Franco on Chronic) is on holiday in Acapulco with his sister Alice (Charlotte Gainsbourg) and her children Colin and Alexa (Samuel Bottomley and Albertine Kotting McMillan).

All seems to be going happily - lazing around on the beach, swimming, drinking - until Alice receives a phone call and is told their mother is dying.

Hurriedly the Bennetts pack and head off to the airport.

Then Neil announces he's left his passport at the hotel and tells the others to go and he will follow on a later flight.

But when he gets into a cab, Neil simply says to the driver, "hotel" - not naming the one where the Bennetts were staying. When he arrives at the driver's selection, he checks in and carries on much as before - hanging out on the beach, eating, drinking, and eventually taking up with local woman, Berenice (Iazua Larios).

Alice's increasingly frantic phone calls are initially met with glib excuses and assurances.

Then he starts ignoring her calls, voicemails and texts altogether.

What is going on here?

This is a film to experience as it unfolds so there won't be any big spoilers here. Suffice it to say it won't be for all tastes but if you're patient and in the mood for something different - roughly akin to reading a literary short story - it's worth catching.

Roth, like Franco, is a talent who's been around a while but hasn't received all the attention he might have, despite appearing in some Quentin Tarantino movies.

His contemporary and co-star in Rosencrantz and Guildenstern Are Dead, Gary Oldman, has gained a higher profile - and an Oscar - but Roth has also had a long and varied career on screens large and small.

He's an intriguing presence, someone whose gaze can be hard to penetrate and who's not always exactly ingratiating but not necessarily hateful. He's an actor rather than having a set star persona.

Roth is well suited to the role of Neil, who seems affable and pleasant - if quiet - at first but whose behaviour becomes increasingly mysterious behind an almost deadpan facade.

No matter what happens to him - and plenty does, including tragedy, robbery, arrest and sex - his demeanour changes little but he remains interesting rather than becoming wooden.

We're looking at a man from the outside, trying to crack the facade to find out what is driving his behaviour.

More information and clues are offered along the way and a possible answer at the end. But, just as at the end of Psycho (1960), glib explanations don't entirely satisfy. It feels like there's more going on than we know, some sort of existential crisis, perhaps.

But maybe there isn't, and that might frustrate some viewers.

Sundown is a relatively short slow-burn of a film, with much use made of silences and sunshine and the Mexican setting.

The feeling can - and sometimes does - shift from cheery to chilling in a flash but mostly there's an undercurrent of unease, similar to that in Roman Polanski's best films.