Buzz Corry, the Commander of the Space Patrol is in route from the planet Terra to Earth. He is accompanied by Cadet Happy, a new Cadet and winner of the Corry Scholarship. They spot what appears to be a derelict guided missile. As they move to destroy the derelict, its engines fire and the missile launches toward the commander's craft. The missile narrowly misses and changes course to intercept. In reality, the missile is a disguised ""cosmic"" bomb controlled by Major Gorla from his fortress on Kars. The Major is assisted by Matra, an assistant to Terra' Secretary General. Together they plan to conquer the United Planets beginning with the murder of Commander Corry.

Marta enlists the aid of Lt. Krasnoff a disgruntled Space Patrol to steal top secret materials and to destroy Commander Corry. Krasnoff holds a grudge against Major ""Robbie"" Robertson, United Planets Security Chief. Krasnoff paralyzes the Major with a ray gun and disengages the magnetic force control causing Buzz and Happy's rocketship out if control and into freefall seconds before landing.

Cabinet member Baron Von Kreitz hatches a plot to overthrow the General Secretary of the United Planets. The Baron sends Lt. Groat to prevent Commander Corry from delivering a report on Venus to the General Secretary. The information is passed to the Assistant Security Chief Tonga, who is wounded and partially paralyzed and imprisoned in the aft compartment of her space car. She manages to activate the ship's magnetizer, leaving a cosmic static trail. This signal allows Commander Corry and Cadet Happy to track her space car to the Baron's hideout on Earth's moon.

Carol Carlisle, the daughter of the Secretary General, is testing her invention she calls the ""Agra Ray."" The radiation from the device enables plants to reach full maturity within a number of hours. However, the ray may be perverted into a powerful weapon with the capability of turning entire cities into stone. Unknown to Ms Carlisle, her assistant is agent of Prince Greegor of Mercury. The lab assistant steals the Agra Ray and kidnaps Ms Carlisle, transporting them to Mercury, where Prince Greegor plans to threaten Terra, the Capitol of the United Planets.

Due to an extreme food shortage in the Juniper system, Major Robertson and Tonga are to transport the Agra Ray to prevent starvation in the colonies. They are met by the sinister Goron, posing as the Agricultural minister, He leads the to his headquarters at the foot of Cornicus' crater. He plans to steal the Agra Ray to force the growth of the ""ivy of death."" The vines give off a suffocating dioxide which he plans to use in destroying the Unite Planets.

Tonga is dispatched to Saturn's third moon after reports of trouble at the Cosmic Radiation Plant #1. Tonga's investigation leads the dismissal of the hot-tempered Captain Kronk. Kronk avows revenge and Tonga is shot with a shock rifle. Commander Corry and Cadet Happy arrive and rescue Tonga, but they are unable to capture Captain Kronk. However, they do arrest Kronk's assistant attempting to abscond with embezzled payroll accounts from the plant.

Cadet Happy makes his first solo flight to the Jupiter Space Port. Unfortunately, he acquires an unwelcome passenger named Lucky. Lucky is by trade an embezzler who is fleeing with Jupiter Trust Company's funds. To insure Happy's silence and cooperation, Lucky threatened to kill Carol and Commander Corry.

The United Planets Chief Astronomer discovers a planetoid has exploded. He sends an urgent report to Major Robertson at Space Control the debris posses a danger to all space raft in the area. Commander Corry, Cadet Lucky and Carol are returning to Terra from Earth when their space craft is struck by a meteor. They find themselves in dire straights: unable to navigate, unable to communicate, and venting oxygen through a hull rupture.

The owner of six lead mines on the moon Planos reports that an epidemic is spreading through the mines. Berger, the owner asks for assistance from the United Planets. Commander Corry, Tonga and Cadet Happy are dispatched on a rescue mission with the needed serum to halt the disease. However, Burger and his assistant are trying to keep quiet a secret discovery of a rich deposit of Exonium. Captain Happy discovers Leckner tampering with the atmospheric controls in one of the mine shafts. In a struggle with Cadet Happy, he unknowingly inhales a lethal dose of the concentrated bacteria.

Warden Sovak and his head trustee, Erik, have been arranging for prisoners to escape provided they can pay the appropriate fee. The prisoners are lead out through a tunnel which passes under an irrigation canal. After the report of three prisoners escaping the supposed escape-proof facility leads to an investigation. Commander Corry, Cadet Happy and Major Robertson carry out the inquiry.