A satellite is launched into space when, as it settles into orbit, it collides with the gelatinous mass of a Space Cell. Soon thereafter, a jewelry store in Tokyo is robbed of its diamonds by a mysterious force right before the startled eyes of a gang of safecrackers. The criminals flee the scene after the mysterious force levitates them away from the safe.
Detective Komi visits Dr. Munikata’s home late that night after following a man to the house. The man, American Mark Jackson, gets the drop on Komi and quickly makes his escape, only to be captured by the gang of jewel thieves on the road outside. Thinking Jackson to be a rival, the gang’s boss believes that he was responsible for the incident at the jewelry store. Jackson does nothing to allay their suspicions, having a pouch of diamonds taken from Dr. Munikata’s house on him.
At police headquarters, Dr. Munikata admits to Komi that the diamonds that were taken by Jackson are artificial. When this is discovered by the jewel thieves, they send Jackson away to be locked up. With only two guards to deal with, Jackson quickly makes his escape.
Taking Dr. Munikata’s secretary Masaio home, Detective Komi meets her brother Kurino, one of the men who launched the satellite. Soon, the same sound Kurino heard when the satellite was destroyed fills the air. Suddenly, the nearby coal yard is attacked by an unseen force. Coal rises into the air, consumed by something in the sky.
Komi follows Jackson to Ginza, this time getting the drop on the American in his hotel room. Jackson tricks Komi with a toy gun and again escapes from the detective. Back at headquarters, the police chief lets Komi know that similar diamond thefts are occurring all over the world.
On a lonely road, the jewel thieves make ready to ambush an armored car carrying diamonds. With Akiko lying in the road, as though hit by a car, the drivers stop and investigate. The bandits waylay them but are interrupted when Jackson arrives. A gun battle ensues and one of the thieves commandeers a passing coal truck to ram Jackson’s car. Suddenly, the coal truck is lifted into the air and the coal sucked into the sky. The truck falls back to earth and crushes the armored car. In the confusion, the diamond thieves escape.
At headquarters, Komi decides that some sort of monster is responsible for the coal and diamond thefts. While in conference with his chief, Masaio calls Komi to tell him that Mark Jackson is at Dr. Munikata’s house. Jackson waits for the police and tells them that he is an insurance investigator, a Diamond G-man, trying to find those responsible for diamond thefts around the world. Jackson agrees to work with Komi from now on.
Back at their hideout, the diamond thieves find their latest haul to be nothing more than sugar crystals, explaining why the monster left them alone and only ate the coal.
At Dr. Munikata’s house, the space commission forwards a report regarding how the space monster was created while speculating on the monster’s habits. Suddenly, a glowing mass of protoplasm breaks through the doctor’s window and attacks his safe. The monster is named Dogora and the military makes plans to protect the cola fields of Kyushu. The doctor goes to Kyushu to study the monster if it attacks. Mark Jackson also heads for Kyushu but is met on the train by Akiko who tries to find out where the diamonds are. Jackson tells the woman nothing, prompting her to report to the rest of the gang.
After meeting with General Iwasa, Dr. Munikata watches Dogora as it arrives over Kyushu. Hurrying to the command center, it is discovered that a swarm of bees is in the same area as Dogora. Soon a rain of rock-like substance showers Kyushu. It is solidified pieces of Dogora.
The gang arrives in Kyushu, following Jackson to his hotel. Komi is waiting for Jackson in his room. Jackson again assures the detective that he does not have the diamonds. In the room below, Dr. Munikata is trying to draw a connection between the bees and the shower of rocks.
Dogora begins its attack on Kyushu, sucking all the coal from some of the coal yards despite the concentrated fire from several anti-aircraft batteries. Dogora lifts a large suspension bridge into the air before a rocket attack finally drives it off. The rocket attack does not destroy Dogora, however, but only splits it into thousands of smaller creatures.
Dr. Munikata discovers that bee venom causes a chain reaction that crystallizes Dogora’s cells. It is decided to synthesize the insect venom and use the toxin against Dogora. Production begins on the toxin all over the world.
As Mark Jackson prepares to leave Kyushu he is interrupted first by Komi and then by the diamond ring. The thieves keep the men prisoner and tie them up. Akiko departs with Sabu to collect the diamonds from a safe deposit box Jackson had a key for. Meanwhile, Dogora again attacks the coal fields. Sabu returns alone; Akiko has taken the diamonds for herself. The gang leaves Jackson and Komi after lighting the dynamite tied to the men. Komi and Jackson manage to escape and pursue the thieves.
Dogora continues to ravage Kyushu while General Iwasa awaits the arrival of the toxin. The monster sucks more and more coal into the sky.
Akiko arrives at the beach where a boat is waiting only to have the rest of the gang arrive and capture her. Before she can be put on the spot, however, Jackson, Komi and the police arrive. The gang scrambles for cover and a running gun battle ensues. When Akiko uses the confusion to try and slip away with the diamonds, she is shot dead by the gang’s boss.
Meanwhile, helicopters arrive carrying the toxin even as great sprayers are positioned on the ground. Toxin is sprayed on Dogora from above and below, quickly killing the monster as great chunks of rock-like substance fall from the sky.
On the beach, the shower of stone threatens both thieves and police. As the gang races for cover, a large chunk of Dogora lands on the criminals, killing them.
The space monster and the diamond thieves dead, Jackson returns to the United States with Dr. Munikata who is going to speak to the United Nations about harnessing space cell energy.