This slow-burn, modern psychological thriller from Scotland takes time to build, but the moody realism pays off in the end.

Jackie is a CCTV operator who spends her working day in front of a bank of monitors surveilling the streets of Glasgow for trouble. One day she recognises a man from her past on a rundown, highrise housing scheme, called the Red Road. Clearly upset that the man has received early release from prison, for reasons not revealed to the audience, she takes a bus to the housing estate and stalks him as he goes about his business.

Clyde (Tony Curran) is a brutish womaniser, so it is surprising when Jackie slips nervously into his life, becoming increasingly intimate with him. As this dangerous undercover game proceeds to its unknown, but apparently vengeful end, the questions multiply and hang in the air. What is the history of this pair? What are Jackie's intentions? Will there be blood on red road by the end?

The plot stretches credulity in several ways: too much reliance on coincidences and Jackie's motivation. Would a vulnerable woman be putting herself in harm's way like this? To the director's credit, the film is sufficiently immersive and has such a pungent air of authenticity that these things do not matter too much.

Good casting of what could possibly be non-actors in peripheral roles and the wise decision not to tone down the broad Glaswegian accents and colourful vernacular for consumption outside of Scotland helps maintain that gritty realism. The low-lit, bleak setting of the estate, graffitied and strewn with windblown plastic bags is spot on, while adding to the dark mood and the increasingly edgy nature of the proceedings.

At the heart of Red Road is a strong sense of reality shifting. This is played out in the artfulness of director Andrea Arnold's compositions. Some might find moments a little too self-conscious - for example, putting Jackie within the frame of a pub server window as if she were in a film frame - but there's also an evocative and poetic quality to the imagery that she chooses here, enhanced by some minimalist sound design. With its deliberate pace, the film acts also a meditation on voyeurism and how surveillance affects daily human relationships.

The lead performances are particularly memorable. Kate Dickie gives such an absorbing and richly textured performance that she carries you along where Jackie's actions might otherwise have seemed questionable. Tony Curran gives a versatile performance, both odious and sympathetic by turns.

This is the first of three Scottish-set films from the Advance Party concept, which is being developed by Lars von Trier's Zentropa Productions. On the strength of this, a winner of a Cannes Special Jury Prize, the other two are something to look forward to.