The middle-aged Olivier (Olivier Gourmet) teaches carpentry at a centre for disadvantaged boys in an unnamed Belgian city.
Why, though, does he spy on one of his new trainees Francis (Morgan Marinne) after initially refusing to take on the teenager? (He even steals a key and lets himself into the boy's flat.) And why does Olivier's ex-wife Magali (Isabella Soupart) react so aggressively when she learns that the youngster has become a pupil of her former husband?
Those who admired "Rosetta" will be familiar with the distinctively minimalist aesthetic of Belgian filmmakers Jean-Pierre and Luc Dardenne.
In other hands "The Son" might have become a straightforward revenge thriller. Yet the Dardenne brothers shy away from melodramatic flourishes: there's no music on the soundtrack, the performances are understated, and it's the gestures of the characters which are psychologically revealing rather than the dialogue.
The visual style is claustrophobically disorientating. Alain Marcoen's handheld camera doggedly follows the stolid figure of the bespectacled Gourmet, framing his bulky physique within the confined spaces of the workshop, the car, and the saw-mill.
Gourmet is also repeatedly shot from behind, so that we see the back of his neck rather than his face. This adds to the sense of suspense and unknowing, whilst the jerky cuts suggest his internal agitation.
Like Robert Bresson, the Dardenne brothers focus obsessively on physical and material details, thereby imbuing objects and actions with a spiritual significance.
Certainly "The Son" lends itself to being interpreted as a religious parable - hence the title (which the directors admit could easily have been called "The Father") - with the choice of Olivier's profession as a carpenter, the repeated washing of hands, and the possibility of forgiveness suggested by the moving conclusion.
In French with English subtitles
The Son (Le Fils) (2003)
