(First Aired: August 7, 1966)
Screenplay by: Ryu Minamikawa
Directed by: Samaji Nonagase
A rocket carrying six nuclear bombs is launched to Jupiter for some studies, but the launch ends in disaster when the rocket crashes into the Pacific Ocean instead. One of the bombs explodes while four are recovered with no problem. The sixth and most powerful one is missing despite extensive search. Worse still, the safety device is broken, judging from the other four, and the bomb explodes twenty seconds after activation. Science Patrol has been asked to think of a way to find the missing bomb with no danger, but Fuji is leaving for vacation to the Hayama Marina Resort with Hoshino as company.
Later, Science Patrol receives a report that one of the bomb-searching ships was sunken by something with only a single sailor left alive. Hayata is instructed to meet the sailor at the Setagaya National Hospital to learn what he saw. In the hospital, the sailor is in a delirious state, only able to speak about seeing a huge white wake, a monster, and the bomb. Hayata reports this, to which Muramatsu connects to another report where an American cruise liner saw a massive white wake too, except it was 100 kilometers closer to Japan than the area of the ship sinking. The two figure out that the mystery wake is probably heading for Chiba, so Hayata decides to go there.
At Hayama Marina, Fuji and Hoshino are enjoying their vacation greatly, now also accompanied by a little girl named Michiko, whose parents have left her in Fujis care while they go shopping. While having lunch, Michiko notices Fujis communicator and turns it on. From it, Fuji is able to pick up her teammates discussion about the white wake heading for Chiba. Hoshino then spies a white wake moving towards their resort. Concerned, Fuji calls Muramatsu about her sighting, so Arashi is sent over on the Jet V-TOL. Ide is left to manage communications in Fujis place. Back at Hayama Marina, Fuji and Hoshino have taken Michiko to bed for a nap when Muramatsu instructs them to have the hotel evacuated as the white wake is now dangerously close. Muramatsu then instructs Hayata to head to Hayama Marina, so Hayata drives off to the nearest ferry dock.
The Hayama Marina is evacuated just in time for a massive tidal wave to signal that whatever has made the wake is now rising out of the ocean. Turning around, Hoshino and Fuji spy the wakes creator a towering green humanoid with fish-like fins. Hoshino identifies the monster as Ragon, a creature that had first appeared before Ultraman came to Earth. However, Ragon is normally human-sized, indicating the exploding nuclear bomb had mutated the creature. Worse still, the sixth nuclear bomb is very loosely attached to creatures scales. Then, Fuji and Hoshino rush in to rescue the still-sleeping Michiko. Entering her room reveals Ragons gigantic eyes peering into the window, though Fuji grabs Michiko just in time for Ragon to smash its giant webbed hand through the walls. The trio run towards the hills nearby with Ragon in pursuit. Hayata and Arashi arrive just in time though. However, they cannot fire at Ragon, lest they cause the bomb to explode, so they merely distract it. Unfortunately, their shooting only enrages Ragon, and with every violent flailing it throws at the circling Jet V-TOL, the bomb risks falling from its precarious dangling. The problem worsens when Ragon reveals itself to now have gained atomic breath from the nuclear bomb, successfully shooting down the Jet V-TOL, though Arashi parachutes to safety.
At HQ, Ide remembers a tidbit of information from humanitys last encounter with Ragon the creature is soothed by music! So, Muramatsu has a JSDF ship loudly play music for Ragon. Unfortunately, Ragons mutation has scrambled its brain, so the nice, soothing music only further enrages the marine humanoid. Hayata soon arrives to find Fuji and Michiko, telling them to find Arashi while Hoshino lures Ragon away from them with his shouting. Hayata uses the opportunity to transform into Ultraman!
Ultraman leads Ragon away from Hoshino, but the monsters flailing arms cause the bomb to finally fall off its scales. Ultraman grabs the bomb just in time, but is now left unable to fight back without dropping the bomb. Then Ragon squeezes Ultramans arms, forcing the hero to drop the bomb and activating its twenty second timer! Fortunately, Ultraman is now able to gain the upper hand and kills Ragon with a Specium Ray, sending the mutated fish-man plummeting into the sea. Ultraman then grabs the bomb with only seconds to go. Flying faster than ever, Ultraman reaches space while Science Patrol counts down the remaining seconds. Five seconds later, Science Patrol witnesses a miniscule explosion in the sky. Ultraman has taken the bomb so far it couldnt hurt a single soul, but Science Patrol is left unsure of his fate. Hayata arrives on the scene minutes later, assuring his teammates and the children that Ultraman is alright.