Takeshi Hongo is abducted by the evil organization Shocker. They turn him into a cyborg in order to conquer the world, only for him to escape and turn against his captors.
Hongo wins the championship, but the model who brings him his bouquet suddenly bares her fangs and attacks! With growing suspicion, Hongo investigates the woman's home, and finds it has been transformed into a lab.
At an amusement park's botanical gardens, people begin to go missing. The young boy Kenji's older sister Yukie gets snatched away, and he tries to tell someone that his sister was attacked by a giant King Sarracenian!!
While a series of strange earthquakes are going on, Hongo is contacted by his childhood friend and seismologist, Amemiya Chikako, who tells him, "Something is planning to cause a major earthquake."
Former navy lieutenant-commander Sunada is attacked by the Chameleon Man. His aim is a submarine model in Sunada's possession that has secrets relating to a Nazi treasure concealed inside.
Takeshi begins an investigation into the series of incidents where people who had glasses made at Kagemura's Optometry store have gone missing. However, even Ruriko gets some lure glasses, and she disappears as well.
Cobra Man makes an attack on the gold vault, but when the pet dog of security guard Kondo barks at him, he drops his fangs! Seeking his fangs, he attacks Kondo.
As noted in the title, it features the return of Cobra Man who was destroyed by Kamen Rider in the previous episode, marking two milestones in the Kamen Rider Series, the first instance of a kaijin being revived and the first instance of a kaijin being improved or "remodeled".
Since all of their previous monsters have been defeated by Kamen Rider, Shocker tries to combine all of their strongest traits in a single monster who will be their ultimate assassin. Gebacondor needs the blood of young women to be activated, and so Shocker targets newlyweds.
Doctor Shirakawa has invented a death ray but tries to seal his invention away, while his aid Shibata conspires with Shocker and is remodeled into the monster Geckogeras, making secret plans to take the death ray.
To break through the Toyo Atomic Energy Research Laboratory's barrier, Shocker remodels pro soccer athlete Nomoto and produces the monster Tokageron with powerful kicking might.
Hongo leaves Japan to pursue Shocker plots in other countries. Meanwhile, Cactogron, a cactus monster who is the head of Shocker's Mexican base, is brought to Japan to try to improve its success rate. And Taki and Tobei find their investigations into Cactogron's plans interfered with by a mysterious man
Shocker's discovered a living specimen of a prehistoric creature called the Pirasaurus which can give off an extremely toxic mist. It's so toxic it kills the very modified human given its poison, however, and Shocker targets a wrestler as being a human strong enough to survive it.
While the monster Hell Thunder enacts his plan to make an artificial antlion pit that tears main roads into pieces, the supreme commander Colonel Zol is dispatched from Shocker's branch in the Middle East.
Zol creates the centipede monster Mukaderas. He then rounds up Japanese children and the monster hypnotizes them. He then revives Sarracenian and Gebacondor to guard the operation. Meanwhile, a hypnotized girl asks Goro to join.
Shocker schemes to turn Tokyo Bay into a sea of flames by pouring in petroleum from industrial areas, equipping the monster Mogurang with an Electro Eye that he uses to capture humans.
Doctor Origuchi of the Criminal Research Institute looks into Shocker's evil doing, and discovers their plan to split the Japanese islands with a special nuclear weapon.
Colonel Zol executes his Wolf Strategy to make werewolves with the Wolf Virus. In the midst of this, the young girl Kumiko from the Wakakusa Garden orphanage witnesses one of these experimental wolfmen.
Shocker plots their "Snow Strategy" to melt all of the snow of Kusatsu Heights and cause a great flood, and makes the physicist Doctor Mikawa manufacture an energy bomb that releases intense heat.
