Simon toys with Underdog who is now in his power after stepping into one of Simon's Phoney Booths. He makes him dance, bring the 1st National bank to him, and then has him retrieve the Empire State Building. Meanwhile, O.J. Squeeze, Sweet Polly's boss, informs her that Underdog is in Simon's power. Polly takes it upon herself to go out with an axe and destroy the booths. When Simon catches wind of this, he sends Underdog out to destroy Sweet Polly. Underdog arrives at Polly's location and she is trapped.

More unsuspecting people fall prey to Simon's Phoney Booths. A banker steps into a booth and is ordered to bring all the money from the bank. An engineer steps into a booth and is ordered to bring his train to Simon's lab. A colonel steps into the booth and is ordered to bring the army to Simon Bar Sinister's house. On a college campus, students try to see how many they can fit into a booth, but of course, it's a Phoney Booth. Each emerging student is told to do a task. News finally gets to Shoeshine Boy who steps into a booth to become Underdog, but, it is a Phoney Booth.

Cad, Simon Bar Sinister's henchman, replaces real phone booths with Phoney Booths. When he returns to the lab to tell his boss all the booths have been replaced, he asks what they do. Simon demonstrates by deceiving the milkman that his office wants him to call and directs the unsuspecting milkman into one of the Phoney Booths. The booth jumps and spins and when it opens, the milkman emerges in a trance repeating 'I will do what Simon says'. Simon instructs the milkman to destroy all his milk bottles, then remotely tells him to drive his milk truck into a pole. Then he tells him to go home and await further orders.

Polly finds Underdog's ring. He takes his energy pill then defeats Electric Eel, Riff Raff and Batty Man. Simon uses his vacuum gun but since Underdog has his powerful strength back, this time it doesn't work. Using his atomic breath, Underdog beats Simon and Cad and returns all the money.

Underdog's ring has fallen off his finger; Polly dives underwater to find it. Meanwhile, Simon and his army are using their vacuum guns to steal all the money in the US.

Sweet Polly is captured by Simon and calls for Underdog. Unfortunately, his energy was drained from saving the ship so he and Polly were sucked in the vacuum gun and Simon starts to fill it with water.

Simon Bar Sinister makes a vacuum gun which he uses to catch Riff Raff, Electric Eel, Batty man and all of their men for his army while Underdog is saving a sinking ship.

Batty Man, a take-off of Bela Lugosi's Count Dracula is an evil vampire. He, with his hench-bat Georgie and his army of giant vampire bats are committing the crimes all over the country. Polly and Underdog investigate the mysterious goings on at Batty Man's castle. The pair are attacked by Batty Man. Underdog tries to fight off the evil villain's bat army, but the battle is too much for him and the duo are soon chained.

The Electric Eel traps Underdog in his electric cage. As the cage closes in around him, the cage fills Underdog's body with thousands of volts. Before he dies, Underdog asks the villains not to throw him into the city's lake. Underdog's body is soon limp at the bottom of the electric cage. Sensing victory over his foe, the Electric Eel takes Underdog's body to the city lake and throws it in. Free from Underdog, Electric Eel begins his massive crime wave across the city. Still not satisfied, the Eel decides to commit the ultimate crime.

In the final episode, the giant finishes toying with Underdog and bats him back to the hospital. With Underdog out of the picture, the Army, Navy and Air Force is called into action against the giant. The giant conquers all the armed forces. Polly explains to Underdog that they were all defeated. Hearing this, Underdog tries to leave, but Polly grabs him by the charm around his neck. In the tug-of-war the charm breaks and Underdog is no longer dizzy. Underdog faces the giant and then punches him so hard, he lands back to his home planet.

When Underdog gets dizzy during an interview after returning from a strange planet, he is rushed to the hospital where the doctors try to find the cause. Meanwhile, the alien grows so big, he breaks out of the lab where he was being examined. Underdog hears the cries for help and leaves the hospital to face the now giant alien. But the charm around his neck causes him to get dizzy, and the giant toys with him.

After returning from a strange planet and wearing a charm that the alien from the planet he brought back to Earth with him, Underdog is interviewed by Sweet Polly about the rescue and retrieval of the alien. However, once he stands up, he becomes dizzy as things begin to spin around. Back on the strange planet, Zorb explains that as long as Underdog wears the charm around his neck, he will become dizzy. He then checks on Cron, who is being examined by scientists. Cron is caged when he becomes agitated. He then takes a pill Zorb gave him which causes him to grow and break free.

Sweet Polly is reporting a launch in space but the capsule is pulled off course to an uncharted planet. On this planet, the evil Zorb used a magnet to pull the capsule to his planet. Zorb explains to his henchman, Cron, his plan to use the capsule as a decoy to lure Underdog. The capsule lands on the planet and gets stuck in the mud. A call is made to Underdog to rescue the planet. After freeing the ship, Cron approaches with a charm and puts it around Underdog as a gift. Underdog, thinking he is a friend suggests to bring Cron back to Earth.

Polly pulls the handcuffs off of the pole and cries over her now-paper hero. Then she hears the familiar saying, "The secret compartment of my ring I fill with an Underdog energy vitamin pill." She sees Underdog is flat but all right. She finds a flat energy pill in the ring and when she give it to him he breaks out of the Valentine, takes the handcuffs off her hand and they fly to City Hall. There, Underdog saves the mayor and stuffs Simon, Cad and the two henchmen in the machine. Polly turns them into Valentines.

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.

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.

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.

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.

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.

After too many foiled robberies, Riff Raff takes his crime gang out West.

Sweet Polly Purebred is a prisoner in Riffraffville and only Underdog can save her. But without his Super Energy Pill, has he met his final match?

Sweet Polly Purebred is a prisoner in Riffraffville and only Underdog can save her. But without his Super Energy Pill, has he met his final match?

Sinister and Cad invent another evil device they call the Big Dipper, a machine that can dry up all of the world's water supplies. On its first trials, the Big Dipper does little more than flooding Simon's lab. After a few false starts, the Big Dipper is finally ready to destroy the world's water supply and Simon may finally have a means of taking over the world!

Simon invents the Valentine Vault which turns people into paper valentines. He orders Cad and his two henchmen to kidnap Sweet Polly... to set a trap to catch Underdog in the machine.

A series of crimes are being perpetrated all over the country. Underdog tries to solve them, but finds no clues as to who is behind the crime wave. Who is the new super villain behind the crimes that are paralyzing the country?

Batty Man has captured Polly and Underdog. The villains raid Fort Knox, returning to Batty Man's castle with the plundered gold. The villains press the gold into a bowling balls. Before long, all the gold bricks are molded and painted black. The villains plan to fence the disguised gold in Europe while posing as bowling ball sales reps. Before they leave for the docks, Batty Man and Georgie place Polly and Underdog onto the conveyor belt that feeds the bowling ball press.

Polly and our hero have been placed onto the conveyor belt of Batty Man's bowling ball presser. The steam from the machine loosens Polly's chains, enabling her to give Underdog his super energy pill. His strength renewed, Underdog flies out to capture Batty Man, Georgie and their bat army, recovering the gold. Our hero returns the gold to Fort Knox and then turns the villains over to the authorities.