In the distant future of 2130, the deep space research vessel, USS Palomino, is engaged in an ambitious quest to uncover signs of intelligent life beyond our world. Captain Dan Holland (Robert Forster) leads a diverse crew that includes the skilled first officer Lt. Charles Pizer (Joseph Bottoms), the ever-resilient utility droid VINCENT (voiced by Roddy McDowall), the capable navigator and science officer Dr. Alex Durant (Anthony Perkins), the empathic medical officer Dr. Kate McCrae (Yvette Mimieux), and the tenacious embedded journalist Harry Booth (Ernest Borgnine). After five long years yielding no results, the weary crew is finally making their way back home for a much-needed refit when VINCENT detects a massive, swirling blue accretion disk, suggesting a course correction. Upon further investigation, VINCENT identifies this disk as a black hole—the largest ever documented.
As the crew discusses the potentially devastating implications of their discovery, VINCENT surprises them by pointing out a seemingly abandoned ship hovering dangerously close to the black hole's event horizon. This peculiar vessel, identified as the USS Cygnus, was last helmed by Professor Hans Reinhardt (Maximilian Schell), a German scientist who vanished almost two decades ago after ignoring recall orders, leaving both his mission and his crew behind. For the crew of the Palomino, the mission has a personal touch; Frank McCrae, the Cygnus's Executive Officer, is none other than Kate's father.
Against his instincts, Holland reluctantly agrees to Pizer and Durant's urging to approach the Cygnus. Struggling against the black hole's colossal gravitational pull, the crew discovers that the gravity diminishes unexpectedly as they near the Cygnus. Speculation abounds regarding the mysterious force that allows this derelict ship to remain intact. Just as they almost succumb to the black hole's grasp, the Palomino manages a narrow escape but sustains significant damage, forcing them to seek refuge aboard the Cygnus.
Upon docking with the Cygnus, the crew disembarks—except for Lt. Pizer—only to find themselves targeted by automated defenses. An unexpected confrontation erupts when they stumble across sinister humanoids clad in hoods and mirrored faceplates. These figures are eventually revealed as the crew, whose minds have been altered by Reinhardt through a series of lobotomies. When Dr. Reinhardt finally makes an appearance, he claims to be the last human aboard, explaining that following a meteor storm that disabled the ship, he and Frank stayed behind while the remaining crew tried to reach Earth—never to be seen again. Reinhardt harbors grand ambitions of piloting the Cygnus into the black hole, eager to explore uncharted dimensions.
The meeting escalates when Pizer is apprehended by Reinhardt's robotic sentinels. While he manages to appease the humans with the promise of spare parts to repair their ship, underlying tensions loom. As startling truths about the Cygnus's crew begin to surface, Holland and Booth express their growing suspicion of Reinhardt's sanity. They stumble upon a lush garden within the ship that raises further questions and concerns.
Over a lavishly designed dinner, the intrigue deepens as Reinhardt speaks of his findings. However, the Palomino crew's unease grows when they discover discrepancies in Reinhardt's turbulent history and motivations. The sense of dread escalates when VINCENT, assisted by the aging sanitation droid BOB (voiced by Slim Pickens), learns that the humanoids are actually shell-shocked former crew members, now mere shadows of their former selves.
A series of thrilling events ensue, with VINCENT and BOB rallying the Palomino crew in a desperate bid to rescue Kate from being lobotomized. As they clash with the robotic sentinels, the stakes rise swiftly, leading to catastrophic failures aboard the Cygnus as it faces the onslaught of meteors from the approaching black hole. Amidst the chaos, even Reinhardt's fate takes a dark turn as the ship careens toward destruction, culminating in a confrontation that sees VINCENT prevail against the formidable Maximilian.
In the explosive finale, the surviving crew members must navigate the treacherous aftermath, fleeing aboard a probe ship as the Cygnus spirals into the mouth of the very black hole they sought to explore. With their lives hanging in the balance, a climactic journey awaits as they plunge into the abyss, enduring haunting echoes of the past that lead them to an unexpected revelation. As they break through the oppressive darkness, a glimmer of hope emerges—a radiant light that signifies a path to salvation, guiding them to safety and a welcome escape from the cosmic horrors they have beheld. The survivors, having thwarted the grasp of despair, find themselves reborn in a new realm, leaving the nightmare of the black hole behind forever.
