Plot

Maintenance technician Ted Clifford is possessed by an eerie yellow glow, which ultimately kills him. It transpires that it is coming from a planet called Triton, which captures the Alphans and insists that Helena should become the Eyes of Triton. Before long she is acting just as Ted Clifford did before his death.—don @ minifie-1

While technician Ted Clifford was setting up tools on one of the window sills in Main Mission, preparing a repair job on some equipment, an enormous orange sphere appeared in space undetected, quite close to the moon. It sent a burst of orange light which flashed about Clifford's head. When the light vanished, Clifford stood upright and blank-faced, walking zombie-like to the computer terminals on the opposite side of the room. Several personnel observed Clifford - who was not known for his computer expertise - using both hands to punch the keys on the keypad panel on the wall with lightning speed. Clifford exhibited superhuman strength; subduing Kano, and then Paul Morrow when they tried to physically remove him from the computer panel. As Clifford resumed his manic keypad-punching, Commander Koenig exited his office, observed Clifford's unusual actions, and attempted to restrain him. Koenig ended up pinned to the wall by Clifford's hand around his throat. Clifford then let go, displaying a look of intense pain on his face. He asked the Alphans to help him before collapsing dead on the floor. Suddenly, the moon became the victim of a sudden jolt, almost knocking the personnel off their feet. Unseen by the Alphans, the gargantuan sphere had enveloped the entire moon in a powerful orange beam. The Alphans finally realized their predicament as a whispering alien voice contacted them, informing them that they are the captives of the planet Triton.

The Alphans are unable to contact the sphere, then Paul Morrow announces that there are scattered localized power losses throughout the base. Also, all but four of their Eagles are mysteriously damaged, leaving them defenseless.

It is learned that Ted Clifford had been transmitting classified information to the sphere. Commander Koenig decides to send out an Eagle to their visitors. Professor Bergman doubts they'll arrive unnoticed; believing they're being watched.

Commander Koenig visits Medical to learn the results of Ted Clifford's autopsy. Helena and Dr. Mathias describe seeing a weak pulsating ball of orange light at the base of his brain and cerebellum which then faded away. There was very little brain tissue left to examine; it had melted. Parts of his brain, including the cerebrum, had become enlarged and were performing at a thousand times their normal speed before his death, which enabled him to see and act as though he were a computer.

Carter and co-Pilot Donovan fly an Eagle toward the sphere, which sends out a beam of orange light, engulfing the ship and sending it flailing back to the lunar surface where it crashes.

The ship had only landed about seven hundred meters from the base, but due to rough terrain, a moonbuggy would be unable to make it there. Koenig leads a rescue team, including Helena, on foot toward the crash site. As they're traversing, Dr. Mathias informs the Commander that Donovan is dead but Carter is still alive. Paul Morrow then reports to Koenig that the base's scanner systems have all gone dead, possibly indicating an oncoming attack. Suddenly a ball of orange light forms around Helena's space helmet. Koenig runs toward her, but is knocked roughly to the lunar surface by the aliens' powerful force. Helena's entire body becomes surrounded by orange light, then she vanishes.

When the Commander revives within the Medical Department, Victor informs him that the aliens have abducted Helena.

Koenig and Alan Carter commandeer an Eagle, equipped with a modified anti-gravity shield which will hopefully counteract the alien's forcefield beam. Predictably, a beam of orange light is sent out toward the ship, but the anti-gravity shield proves effective. However, the beam is retracted and the forcefield reverses, sending the Eagle speeding toward the sphere. G-forces pin the two Alphans to their seats, but manage to cut the power to the ship's engines as they both become incapacitated. The Eagle is brought back to Alpha by remote-control.

Meanwhile, Alpha has a new arrival; Helena materializes in a ball of orange light outside one of their airlocks, still wearing her spacesuit.

Dr. Mathias examines Helena, finding her unharmed with the exception of her optic nerve; tests indicate she should be blind, but she obviously isn't. Helena suspects that some of her functions are under the aliens' control. As Helena's explaining her experiences aboard the alien sphere - not seeing any actual beings, only communicating with the same voice they had all heard in Main Mission - she suddenly becomes briefly enveloped in orange light, then starts behaving as Ted Clifford had. She walks toward the room's closed door, then dematerializes. She instantaneously appears in a corridor, then enters Main Mission. When she begins speed-typing into the keypad on the wall panel, Kano informs Commander Koenig that she's transmitting detailed information to the sphere regarding their life-support system. A minute later, Helena stops typing, temporarily released from the aliens' control.

After Helena's been taken over several times in this manner, Victor points out that it would seem that their people are transmitting information because the aliens are unable to leave their sphere. Taking into account Helena's experience within the alien vessel, Koenig suspects that there are no alien beings, only an intelligence. He becomes determined to board their ship.

Dr. Mathias has summoned Koenig and Bergman, explaining that one of Helena's recent medical scans has detected a ball of orange light within her brain - a stronger form than had been found within Clifford. Bergman realizes that the aliens needed to bring Helena aboard the sphere for it to be implanted, which was why it didn't work with Ted Clifford. Mathias warns Koenig that at the rate the aliens have been using Helena, her body won't last too much longer.

Victor has been researching the aliens' origin. Using the computer, current star charts, and a past incident where ancient astronomers recorded evidence of a supernova in the night sky, Bergman comes to believe that the planet Triton no longer exists. Koenig becomes hopeful that if the aliens were made aware of this fact, they may release Helena.

Kano has found a way to jam computer - which should deactivate the forcefield surrounding the moon - just long enough for an Eagle to be safely sent to the sphere.

As soon as Helena's reactivated again by the aliens and begins transmitting more information to the sphere, Koenig lifts off his Eagle which also contains Alan Carter and four security men. As the ship approached the sphere, the usual beam of light is sent toward the Eagle. Koenig orders Kano to start the computer jamming process, which immediately releases Helena as well as the moon itself. The Eagle flies freely into the sphere, which seems to be made of light. Ironically, it appears pitch black inside the sphere.

Kano sets up the computer's memory banks with the only data that Helena will be able to transmit to the sphere.

The Eagle lands on some type of surface and there's a breathable atmosphere outside the ship. Koenig then leads the security team out into the darkness.

Meanwhile, Alpha's computer has just succeeded in clearing the jam Kano had set up, which reactivates Helena. She resumes with her manic high-speed typing.

Koenig is suddenly enveloped in orange light and transported to the aliens' control center. The whispering voice informs him that they were aware that Alpha's computer would be jammed and had allowed the Eagle to arrive here so Koenig could receive the brain implant; also knowing that Helena's not going to last much longer. The alien intelligence also informs the Commander that their current mission is to learn everything they can about Earth man to prepare for Earth's eventual invasion of their planet, despite the two worlds residing countless light years apart.

Using the information that Helena had been set up to transmit, Commander Koenig successfully convinces the aliens that Triton no longer exists, making their mission obsolete.

Koenig finds himself once again at the Eagle, so he hustles the security team back inside. They hastily lift off as the sphere begins to break up. The aliens destroy themselves as the ship returns to Alpha.

Helena is examined and found to be back to normal, with no sign of the alien implant.