This movie centers around an unusual pair and an enigmatic woman who enjoy participating in risky activities, with one game spiraling out of control. I’ve been devoted to this film ever since experiencing it during my teenage years. It appears fairly mild until a remarkably abrupt and startling occurrence completely alters the narrative's direction. Following that moment, the deliberate pacing amplifies the feeling of anxiety, anticipation, and confusion surrounding the unfolding events, leading up to an unexpected and tragic conclusion. It’s undoubtedly among the most overlooked films from the nineteen sixties and remains a cherished film throughout my life. -- DrNostromo.com

Source on TMDB