Is there any more terrifying notion than being confronted by a loved one who has somehow changed from the person he or she once was, and being helpless to do anything about it? Sure, they may look the same on the outside, but the very things that make them who they are—their personality, their emotions, their capacity for empathy—have suddenly flickered out like a lightbulb that has gone black. This is the very situation with which Elizabeth Driscoll (Brooke Adams) is suddenly faced, and it is so crazy and unimaginable she can barely comprehend it herself. One day, she and her fun-loving doctor boyfriend, Geoffrey (Art Hinde), are going about their lives like any other. The next morning, Elizabeth wakes up to a different man, one who sounds and looks like Geoffrey, but who in all other ways has seemingly become a compassionless blank shell. At first, Elizabeth questions if he is angry with her for some reason, but no, that's not it. Geoffrey is not Geoffrey, and the longer she moves around the streets of San Francisco the more she notices other people aren't themselves either. Something is definitely wrong, and it is sweeping across the city like a dirty, conspiratorial secret of which she is not a part.

Jack Finney's 1955 science-fiction novel had previously been successfully adapted for the screen in 1956 by director Don Siegel, but Philip Kaufman's 1978 version of "Invasion of the Body Snatchers" is that rare superior remake that manages to explore its subject matter on a deeper, more provocative level while heightening its psychological complexity and jittery disquiet. Director Kaufman and screenwriter W.D. Richter have made a virtually perfect film, a masterpiece of paranoid terror that continues to be, nearly forty years later, a watermark of the sci-fi and horror genres. Impeccably natural writing and richly observant performances led by Brooke Adams and Donald Sutherland, as health inspector friend and colleague Matthew Bennell, plant the viewer in the lives of its believable, identifiable characters, then watches as everything around them contorts into a world they scarcely recognize.

Human emotion and inhuman detachment are at the heart of "Invasion of the Body Snatchers," these diametric opposites driven apart by the opening catalyst—the arrival of a gelatinous alien species to Earth that pollinates plant leaves with pink flowers born from unusual small pods. When Elizabeth finds one of these in her yard, she excitedly believes she has stumbled upon a new breed of flower. She has no way of guessing it is the very first step in a planetary takeover aiming to replace the population with alien drones. Kaufman and Richter spend enough time developing their achingly real characters that the gravity of what they stand to lose—their identities, yes, but also their abilities to love and fear and feel anything at all—means all the more. It is a desperately unsettling premise, one its filmmakers explore with an increasingly manic intensity. Intoxicatingly lensed by cinematographer Michael Chapman, the film builds a practically unparalleled sense of claustrophobia while paying attention to the minutia of everyday life turned unnervingly on its head. When Elizabeth's suspicions are met with a more logic-driven explanation by psychiatrist Dr. David Kibner (Leonard Nimoy), she starts to wonder if her overactive imagination has gotten the best of her—that is, until married friends Jack (Jeff Goldblum) and Nancy (Veronica Cartwright) back her up after having a similar hair-raising experience at the spa they own.

Every frame of "Invasion of the Body Snatchers" is fastidiously captured without accident, sumptuously alive with details large and small, some which may not be noticed on first viewing but that all coalesce both consciously and subconsciously into a mesmerizingly portentous whole. Elizabeth and Matthew are the sympathetic anchors, flirtatious work friends who are unable to admit the love they have for each other until it is almost too late. In better circumstances, they could easily be the stars of a straight drama, one that does not involve monstrous replicas seeking to take their place in life. As a mournfully eerie bagpipe-infused version of "Amazing Grace" floats into these characters' paths the closer they approach an inescapable fate, the picture nears the completion of its witchy spell—but not before an unshakable final scene that never fails to send a shiver down one's spine. Emotionally stirring, visually striking and having not aged a day, "Invasion of the Body Snatchers" cries out for individuality in a skewed, nightmarish totalitarian reality. The results are as squirmily potent in 2016 as they no doubt were in 1978.