The two characters primarily involved in Claude Chabrol's 1969 French thriller The Unfaithful Wife have, at least at the beginning, rather an idyllic and somewhat pleasant set up in their lives. When we first encounter them, we see both the husband and titular wife with their rather extended family in a large garden on a warm, sunny and welcoming day; the tone of the exchanges polite, the activity nothing out of the ordinary nor needlessly extravagant. The opening shots of such imagery are quite crudely broken up by a blurred effect which drowns the screen of its focus, the ideal family unit itself thus becoming difficult to firmly latch one's eyes onto; the credits begin, some rather harsh and somewhat official looking credits that scroll upwards in a military manner whilst some distorting piano music plays overhead. It's a fleeting few minutes or so of idealism in-between such a sequence, the film going on to form a superior mediation on human behaviour masquerading as a causality thriller as paradise is rendered corrupt and peeking beneath the surface of the upper-classes reveals deception and titular unfaithfulness.

The film is unrelentingly fascinating, a piece never for more than a few seconds ever in the slightest bit uninteresting; a grim and somewhat bleak study how love, anger and victimisation brew together to create a cocktail of violence and anguish and how that in itself can come to forge a relationship which was never initially set in stone. The film's methodical lead is Michel Bouquet's Charles Desvallees, a lawyer with his own office located in a small enough building amidst the bustling Parisian streets away from the large, more ruralised country house in which he lives with his family. The family, of which, is made up of the titular wife, a certain Hélène (Audran) who's about the same age as her husband and is the mother to young son Michel (Di Napoli). The warm and welcoming day in the garden spent with Charles' mother and Hélène's in-law turns into evening, Charles' verbal illustrating of various plans he would like to have happen the following day involving both he and Hélène out and about doing things are shot down with casual reasons which excuse Hélène from attending. As they sit and observe a television broadcast later on during the evening, the signal begins to break up and the machine ceases to function as well as it might, thus further insinuating a breaking down of communication of an operative item and echoing their marriage.

At work, and aside from Charles' rich circle of friends and busy schedule, he observes through young female secretary Brigitte (Turri) the very essence of temptation. His suspicion brought about by his wife's behaviour, and Chabrol's own channelling onto the audience of signs and notions towards an upsetting of a paradise-like set up or the malfunctioning of a working order, beginning to resonate. Desperate, as thoughts; feelings and drama all at once clinically escalate, Charles darts to the nearest payphone to call a place of business Hélène said she'd be; the piano music from earlier only suggesting at something seriously wrong with what idealism we were seeing beginning to pipe up again to form the overlying soundtrack to the news she is not where she said she'd be.

The painful inevitable is confirmed when a private detective Charles hires reveals to him the truth; that Hélène is, in fact, having an affair and with a writer named Victor Pégala (Ronet) based not so far away. The film allows Charles a moment you sparsely see in today's age of thrillers; a moment of contemplation that has him stand beside a river flowing through the urbanised locale in which the reveal was announced so as to merely look across to the other side of it, digesting what it is has been exposed to him. It is around about here in the film that Chabrol applies a gear change so dramatic and so effective that it propels the piece beyond its combined brooding roots of paranoia and suspicion and into an echelon of unpredictability; horror and human emotion in its some of its rawest forms. In short, the switch in tone and content works remarkably; the film coming to have Charles journey to the man and see him.

The film's causality infused thrills and scares following the venturing into the territory it goes near does nothing to distract the film from its overall tract; it is a film that is able to evoke just as much an on-edge reaction from its audience following a character's glance or nervous facial reaction as it can from a minor car accident. Chabrol's capturing of some of the interplay towards the conclusion as two people are forced into hiding varying secrets from both one another and the police is fascinating, and the film does not loose sight of son Michel's role as the picturesque representative of innocence caught up amidst all this and made to suffer out of others' ill-gotten decisions. Chabrol's overall ending is decidedly bleak, but his conclusion that the two we examine whom previously appeared to fall away from each other only to reconnect when some sort of duality was established, is dangerously uplifting given the sorts of events which aided in this and the actions the lovebirds undertook; all of it combining to form a superior thriller of an immensely sophisticated ilk.