Underdog breaks out of the phone booth, and hears the cries for help again. Underdog flies to the lady, who tells him that her little boy has been accidentally locked in a bank vault. With only this information, Underdog flies off toward the bank. He reaches a bank, crashes in, much to the shock of the occupants, and then proceeds to rip open the giant door to the vault. The bank president blows up at Underdog, saying that he's got the wrong bank! So, Underdog flies to the correct bank, and attempts to rescue the boy. But at first, nothing he tries works. He crashes through the vault door, only to crash through the whole building and the one next door as well. He tries using his X-ray vision to locate the boy, but instead, starts a fire! All the people in the bank are in a panic now! Underdog uses his atomic breath to blow out the fire, and in the process, blows virtually the whole building away! But at least the mother's little boy is found all safe and sound.

An army of giant robots take over the city and capture Polly. Underdog foils the monsters by using his high-pitched voice to destroy the robots' electronic brains. The robots aren't the only thing destroyed, but so is all of the city's glassware.

Simon, a mad scientist, creates a camera. This is not some ordinary camera however. When he takes someone's picture, the freezes them in the photograph!

Simon Bar Sinister creates a new super weapon: the Go-Snow Gun. The gun freezes people, turning them into snow people. Simon and his Henchman Cad take over the First National Bank, holding the bank President, his staff and customers prisoner.

After Simon and Cad turn the bank president, his staff and customers into snow people, they rob the bank of all its assets. Then they crash a party at a mansion, turn the band into snowmen and rob the guests there. Later, after sneaking into Simon's lab, Sweet Polly Purebred is captured by the two villains. Simon prepares to make Polly his loveliest snow woman.

Capturing Polly in their lab, Simon and Cad are about ready to turn her into a snow woman. But then, Cad comes up with an even more insidious plot: he suggests Polly broadcast an ultimatum to the city: either turn total control of the city over to Simon Bar Sinister and Cad within 24 hours or be frozen to death. Intrigued by his henchman's plan, the two villains take the TV reporter to the center of the city and force her to broadcast his ultimatum. Underdog arrives at the scene to stop Simon, but is frozen solid by the Go Snow Gun.

Simon has frozen poor Underdog solid. All efforts to defrost Underdog fail. Somehow, Underdog defrosts himself and immediately flies around Simon and Cad so fast the two villains get dizzy. They fall down unconscious and are turned over to the law. Underdog then rescues the frozen people by using his super-hot atomic breath, defrosting them all in seconds. The episode ends with a group of people on the street saying "It's a plane," "It's a bird," "It's a frog!" & a man saying "A frog?" with Underdog saying: "Not plane, nor bird or even frog, it's just little old me, Underdog." before crashing into a building.

Underdog is having an average day. He foils a bank robbery, rescued Sweet Polly and made himself useful across the world. Meanwhile, a million, million miles away on the planet Zot, King Klobber is upset. It seams that his daughter the princess wants to get married and can't find anyone suitable.

The story of Zot continues with King Klobber searching the galaxy and then the universe for the strongest warrior. They discover Underdog on an insignificant planet named Earth. King Klobber sends a fleet of spaceships to capture underdog and return him to the planet Zot.

As the story of Zot continues King Klobber of Zot sends a spaceship to capture Sweet Polly Purebred. He holds Polly under "The Great Zot", a 10 ton weight. When Underdog arrives to save Polly he agrees to marry the princess if Polly is returned safely to Earth.

The story of Zot concludes, as Underdog and the princess are about to be married. Just at that moment the evil two-headed dragon attacks the city. Underdog defeats the dragon and saves the city. King Klobber grants underdog a favor and he asks to be allowed to return to Earth without marrying his daughter. The King agrees and the princess decides she was in love with the Prime minister of Zot all along and all are happy.

Riff-Raff is no longer Public Enemy No. 1, so he comes up with the ultimate plan: robbing a trainload of gold by distracting Underdog from his duties of protecting the gold on the train.

Riff-Raff's plan goes into action: they kidnap Sweet Polly Purebred, tie her up and put her in a balloon, and set up a bunch of other balloons with record players inside them playing records of Sweet Polly shouting "HELP! HELP!" Once the plan is under way, Riff-Raff's gang heads over to the train station and hold up the stationmaster, and Underdog leaves his post and heads over to the balloons, only to be confused by the record players.

Underdog is still confused and frustrated trying to find Sweet Polly among all the balloons, so far only coming across the record players Riff Raff's gang implanted in the balloons. But then Sweet Polly's balloon springs a leak and is plummeting towards earth toward a hungry alligator. Underdog then finds the real Polly in trouble and saves her from danger. Meanwhile Riff-Raff and his gang take over a railroad station, planning to throw the switch so the gold train Underdog was guarding will collide with another train.

The train full of gold is about to crash into another train, with Riff-Raff's plan going just as he expected. However, Underdog has just rescued Sweet Polly and manages to make it in time, stopping the two trains before a major derailment occurs. Underdog then chases Riff-Raff throughout the station winds up catching Riff-Raff, and all is well once again.

Sweet Polly Purebread boards a ship to travel to a south sea island to investigate the world's biggest monster "Fearo the Ferocious". Go-Go Gophers: Colonel Coyote thinks a book entitled "How to Fight Indians and Win" will help him succeed in capturing Running Board and Ruffled Feathers. Commander McBragg - Dodge City Dodge: The commander tells of the time he cleaned up Dodge City of it's outlaws with the help of a water tower.

After overcoming a mutiny at sea Polly and the gang continue on to the south sea Island to find "Fearo the Ferocious". Upon arriving at the Island Underdog saves the day as he overcomes ferocious dinosaurs.

Reminiscent of the movie King Kong the gang captures "Fearo" and return him to civilization to meet the public in a big television broadcast. But "Fearo" escapes in a rampage, kidnapping Polly in the process. Go Go Gophers - Who's a Dummy?: The colonel tries a tactic from the football playbook and he and the sergeant fail miserably. Commander McBragg - Football By Hex: The commander tells of the time he single-handedly won a football game at his old university.

"Fearo" runs amok and even the Army cannot stop him. Underdog arrives on the scene and battles "Fearo" by tantalizing him with a jungle delicacy.

Simon Bar Sinister is working an a chemical that will shrink the city's citizens to miniature size. Go-Go Gophers - Tapping the Telegraph: General Nuisance returns with a transmission station and 400 troops. His plan is to keep in contact with the fort and coordinate attacks on Running Board and Ruffled Feathers. However, the Indians get a transmitter of their own and block those messages and send their own. Commander McBragg - Rabelasia: The commander relates his story of the time he outwitted the Secret Service and made off with some plans while working as a spy.

Underdog is shrunk by Simon's new evil device and is placed alongside Polly in a birdcage. Luckily, our hero's powers are still useful and they break out of the cage. Seeing that his shrinking of people with his trick flower is taking up too much time, Simon decides to put his shrinking water into a rainmaking machine. Simon and Cad return to the lab only to be tripped up by a trap set by Underdog and Polly. Simon reverses the trap, and catches the pair inside of a rat hole. An army of rats soon corners Polly and Underdog.

Underdog and Polly are trapped in a rat hole, surrounded by a army of rats. Weakened from their run from Simon and Cad, Underdog needs to regain his superpowers with his Energy pill. Polly gives him his pill and our hero soon clobbers the rat army. Leaving the rat hole, Underdog and Polly new mission is to stop the two villains from shrinking everyone with Simon's rainmaking machine. But at this very moment, Simon and Cad have already set up the device- filled with Simon's evil fluid- on a hilltop overlooking the city. The Machine is already operating.

The rainmaking machine has done its evil work; Simon has shrunk everyone to the size of his thumb, even his henchman Cad. Panic soon grips the city. Underdog and Polly arrive with a plan to capture Simon and make him reverse his formula. Underdog and Polly lead the citizens into the backyard of Simon's lab. Using a leaf, a strand of Polly's hair and a spider's web, our hero swings down and- using his makeshift violin- sends the demented scientist softly to dreamland. While Simon sleeps, Underdog grabs a hold of the shrinking water bottle and pours enough of the solution to shrink Simon to the size of a flea. When Simon wakes up, he tickled by Underdog and Polly until he gives up the antidote. Soon, everyone is back to his or her normal size and Simon and Cad are turned over to the law.

Far beneath the sea in the kingdom of Maldemare, the Empress scorns the Emperor for not taking over the surface dwellers. He informs her that he has 3 of his top scientist working on the problem. The first demonstrates his volcano machine which erupts, but Underdog quickly puts out its spew. His failure provokes the Empress to have him thrown into the giant clam. The second scientist demonstrates an earthquake machine, which, again is defeated by Underdog. He too is thrown to the giant clam. The final scientist has the Emperor and Empress observe his Tidal Wave Machine, which begins to churn under the sea, gradually and eventually causing a giant tidal wave. The Empress instructs him to turn it on. And they wait for the needle to reach the tidal wave point.

The Emperor and Empress of Maldamere have a scientist who has created a tidal wave making machine, and plan to use it to destroy the surface world. Concerned about the giant waves that are threatening the world, Sweet Polly Purebred and Professor Moby Ahab- a noted oceanographer- head for the South Seas to investigate. But their trip to the South Seas are being watched by the evil monarchs of Maldamere. The Empress orders the release of her army of giant whales to stop Polly and the Professor. Seeing the attack, Polly calls for Underdog who foils the whale attack. Angered, but not willing to admit defeat, the Empress orders her guards to capture Polly and the Professor in their submarine. The very moment that their bathysphere reaches the ocean's bottom, Polly sees a strange and horrifying sight.

After being captured by the evil monarchs of Maldemare, Polly and the Professor are taken in front of them and learn of their evil plan. Polly begins to cry for Underdog but is told that he can't hear her down there. Meanwhile, the Navy who was monitoring the expedition, become worried when they lose contact with the bathysphere and Polly and the Professor. They immediately send a message to Underdog who immediately arrives on the scene. Underdog then goes beneath the sea but is monitored by the Empress. She instructs her guards to release the man-eating sharks. After fighting the sharks, Underdog is then grabbed by the 'guard', a giant octopus. Weaken by his fight with the sharks, and almost out of air, he is succumbed and taken to the city where he is thrown into the giant clam with Polly and the professor.

Trapped inside of the giant clam, it looks like the end of Underdog and his friends. Polly remembers to give Underdog his super energy pill, and he tickles the clam into helpless laughter. The trio to escape, but not unnoticed. The Empress has had enough of Underdog's interference and sends her guards to trap the trio inside an inescapable bubble. The guards shoot their bubble-guns, trapping Underdog and his friends inside a bubble-like cage. Polly hands over her hairpin to our hero, and he pops the bubbles, sending the guards running off in fright. Underdog then heads for the gates of Maldamere, where he bests the giant octopus, destroys the tidal wave making machine and forces The Empress and The Emperor to give up their plans for conquering the surface world. Having achieved victory, Underdog returns Polly and Professor Moby Ahab to their ship.

O.J. Skweez comes to Sweet Polly Purebred with news about the Hopeless Diamond being worn at a party. Knowing that some crook is going to steal it, O.J. suggests that Polly will go to the party disguised as a waitress so she gets the first report of the theft. Meanwhile, Riff Raff also gets the news and plans to do the same thing exactly - disguise as a waiter to steal the diamond. Someone also gives Shoeshine Boy the news, telling him that he will have lots of shoes to shine at the party, although, Shoeshine Boy decides to go knowing there will be danger that will call for Underdog. At the party, Riff Raff unfortunately reveals himself when he runs into Polly. He takes Polly to the kitchen and decides to replace the Hopeless Diamond with ice. The lady who wears the diamond freaks out which sends in Underdog, who tells her that her diamond is actually ice. Meanwhile, Riff Raff (and his henchman Mooch) puts Polly in a car and rolls her downward.

Things looked bad for Polly, who's speeding down a car downward on a slope, and a wheel on the car even comes off. Fortunately, Underdog flies down and saves her just as the car falls off the cliff. After dealing with Polly, Underdog announces on the TV news that Riff Raff has the diamond. Enraged, Riff Raff thinks of a way to make sure Underdog doesn't bother him again. Later, Underdog finds signs that lead to Riff Raff's hideout, but in reality, he is lured inside a cave that starts eroding inside when Mooch blows it up. Meanwhile, Riff Raff is looking for an Underdog impersonator. He finds one named Tap Tap who is entirely perfect. Tap Tap and Riff Raff rob the bank, much to everyone's surprise when they see "Underdog" doing a crime.

Tap Tap, disguised as Underdog, has been going all over the place committing crimes. After stealing the mayor's cigars, he goes back to the hideout of Riff Raff and begins to cut the Hopeless Diamond into pieces. Meanwhile, the real Underdog escapes the cave he is trapped in and flies back to town, where he gets shot at everywhere. Underdog is naturally confused, so he visits the mayor who is mad at him for stealing his cigars. Underdog visits the last person who is sure trusts him, Sweet Polly Purebred. Unfortunately, she too doesn't believe him and is upset at Underdog's actions, and he is taken away to jail, much to Underdog's shock.

Underdog is so helpless in jail, that he began to believe that he really did do those crimes. Back at Riff Raff's hideout, Tap Tap has trouble cutting the diamond. Even with the biggest hammer that chops the table, the diamond is still in one piece. Tap Tap figures someone with the strength of a thousand men could chop the diamond. Riff Raff remembers Underdog, and believes that since no one has hope with him anymore, he can join his evil team. They dig a hole to Underdog's cell and tell him the deed after Riff Raff explains that Underdog didn't actually commit those crimes, which hopeless Underdog accepts. However, when they make it to the hideout, Underdog takes the diamond and turns Riff Raff, Mooch, and Tap Tap to the law, finally proving his innocence to everybody. Everyone, including Sweet Polly Purebred is relieved that Underdog is still a hero and apologize to him after Underdog proves to everybody that he didn't commit those crimes.

Underdog's double, an evil criminal, plots to steal a priceless diamond after he escapes from prison.