Roman Polanski's full-length debut is a stunning existentialist exploration of sexual jealousy, social concern and powerplays. Collaborating on the script with the great Jerzy Skolimowski (of Deep End fame to name but one) and an uncredited Gerard Brach, Knife in the Water is almost like an intellectual, abstract version the 1989 popcorn chiller Dead Calm in its study of sexual possession and implied threat.
Andrzej and Krystyna are a sophisticated well-to-do couple en route to a weekend's sailing trip when they come across a young drifter on the road, hitching for a lift. Andrzej not only gives the young student a ride, he also insists that he join them on their yacht. From there, a macho competition takes place between the two men as Andrzej is immediately aware that their guest is attracted to Krystyna.
Andrzej game as host to this captive prey is to exert his power and mark his territory, undermining the nameless young drifter with his possessions, education, athleticism and wealth. However these are all met by the drifter's sheer indifference. The younger man contents himself with playing aimlessly with his pocket knife (complete with Freudian connotations) and, when given a task to perform, more or less excels. In refusing to rise to the bait, he manages to both spoils the older man's game and increase a sexual interest in Krystyna.
From that moment on, this battle of the generations and class (the nihilism and nonchalance versus the materialism and seniority) is scuppered and Andrzej sees it is not going to plan. A physical conflict inevitably ensues in which the drifter's knife goes overboard, soon followed by the drifter himself. Earlier, the young man had claimed he could not swim, putting himself at a disadvantage over the preening athleticism of Andrzej. However, this disadvantage quickly turns to an advantage as it is revealed he lied about his (in)ability.
Andrzej is forced to go in after the younger man both by Krystyna and his own conscience, but the drifter has tricked the older man and returns to the yacht and Krystyna, who informs him that he and her partner are two of a kind and surprises him by showing him he knows more of his frugal, aimless existence than he originally imagined, before succumbing to his embrace and returning to the jetty, without Andrzej.
The film concludes with the drifter disembarking before Krystyna moors the yacht at the jetty, where Andrzej is waiting for her. Their reunion is silent and terse as he busies himself with securing the yacht and returning to their car. Andrzej has justifiably sullen - he failed to best the drifter who he believes has drowned from playing his game, and cannot even find the young man's body. His macho pride wounded as much as his conscience dogged by guilt, Andrzej and Krystyna find themselves at a literal and metaphorical crossroads as the car halts at a T-junction as Andrzej considers his next move; whether to believe Krystyna, who has told him that the drifter tricked him and returned to the yacht whereupon she cheated on him with the youth, or to accept his guilt and hand himself into the police station up ahead. He'd like to believe the former to spare himself the hardship of the latter, but to do so would accept a greater loss at the game and the realisation that he no longer is enough for Krystyna than the accidental death he believes he has caused.
As a debut, this is certainly arresting and stylish stuff. Knife in the Water feels more like a seductive, psychological French thriller or Pinter with its jazzy score and sparse delivery, but the preoccupation with class and generational warfare marks it out as Polish, expressing perhaps more of Skolimowski's concerns than Polanski's. A tense, unsettling affair and thought provoking affair, the cast consists of just the three characters (Leon Niemczyk as Andrzej, Jolanta Umecka as Krystyna and Zygmunt Malanowicz as the nameless hitch-hiking student) who play their parts brilliantly.