The earthlings are transported to a prehistoric land from which no one has ever returned. 

Two giants, Thorg and Berna, have a device called a "Space Time Manipulator" that is capable of sending the little people back in time and allowing the group to avoid their current predicament. To do this, they must relive their original trip again.

The Earthlings are sneaking into a circus to steal explosives when an escaped gorilla captures Valerie. With the aid of an elderly puppeteer, Goalby, Valerie is rescued. Betty then wanders into a bear trap, and Goalby frees her but injures his right hand. Betty and Fitzhugh decide to help Goalby win his audition by becoming 'puppets'. 

The little people are attacked by a giant boy who has been playing with his imaginary friend in the woods with an army of deadly military toys. The boy does not believe the earthlings to be real and carries on firings at will.

More adventures with saboteurs intent on disrupting giant society, as the group becomes embroiled with the mysterious Dr. North, who is planning a major terrorist outrage.

Following a series of assassinations, the little people are accused of the crimes by an ambitious giant journalist who will stop at nothing to get her story.

The group meets a giant inventor who has developed a new device, a teleporter, capable of matter transport over great distances. He is helpful and interested in the little people's problems, but is betrayed by an S.I.D. agent and must face the consequences.

While ducking archaeologists and a mysterious saboteur who fires a gun that causes an explosion, Fitzhugh is wounded and the group takes refuge in a cave. It contains a teleporter, which transfers Dan, Fitzhugh and Valerie into a secret underground city. 

The travelers come across a bizarre giant capable of hypnotizing people with his mysterious flute which, when played, can draw people magically towards it. 

Following exposure to radiation from a new power source -- the Delta Device -- the little people become temporarily invisible to the giants.

The little people come upon a friendly giant who mistakes them for leprechauns. The giant, O'Reilly, assists the little people in obtaining items to help repair their chip, and the group becomes embroiled in a series of adventures with policeman Krenko.

After stumbling upon the space capsule discarded by the earthmen from the year 5477, Fitzhugh and Steve actually manage to get back to earth...but can they remain there?

While stealing firecrackers, Barry and Valerie take refuge in a giant child's balloon, which is cut loose. Mark and Steve hop in, and the balloon is inexplicably drawn west, against the wind and across the 'Sea of Storms'. Dan and Fitzhugh can only listen helplessly as the rest of the group is drawn out of range.

Two earthmen from the distant future (the year 5477) land on the giants' planet with a mission to observe. It transpires that they are more deadly than the giants as their superior technology leads them to a deadly arrogance.

A giant scientist experimenting with cloning technology succeeds in cloning Valerie and Barry. These are returned to the camp -- where they prepare a booby trap to kill the rest of the earthlings.

Steve, Mark, Fitzhugh and Valerie stop a depressed giant from jumping over a bridge, only to be captured by him. The man is Egor Crull, a horror actor fallen on hard times. Egor thinks he can use the little people to jump start his career, so he takes them to Manfred, a third-rate producer stuck with a broken down studio.

Fitzhugh creates a distraction to let Valerie escape from a giant, and gets captured himself. The giant, Deenar, is a wax sculptor and diamond cutter, who wants to make statues of Fitzhugh and sell them. 

Barry's dog Chipper is injured by the barking of a giant German shepherd. Barry, devastated by this, endangers the lives of his colleagues as he takes him to a giant vet.

While fleeing a giant dog and the S.I.D., Valerie and Betty duck into a goldsmith shop where the man is working on a music box/cage for Garak. Garak spots them and captures Valerie, who he plans to use in a plot to kill his uncle. He bets his obnoxious Uncle Tojar, a ruthless millionaire and mechanical toy collector, $10 million that he can impress him.

Barry has learned trumpet playing from Dan and goes to a nightclub with Valerie and Fitzbugh. There, they see the owner, Biff, who is a lousy trumpet player and owes money to a crook, Hanley. Barry loses the trumpet and he and Valerie get captured by Biff who prepares to reluctantly turn them to the SID to make enough money to pay off his debts to Hanley.

After being infected by a mysterious spore found on the giant planet, Steve becomes a dangerous paranoid and seeks to capture his earthly colleagues one by one as he is convinced they are now his enemies.

First Fitzhugh, Barry and Valerie, then Mark, Steve and Dan, are captured by Kronig, a giant industrialist who is a chess fanatic. He wants to demonstrate his superior mind against the Earthlings. To do so, he tells them to pick there best chess player to play with him. If they win, they will get there freedom.

While looking for horse hair at a local racetrack to make a high-tensile cable, Fitzhugh and Barry watch the horse races. Upon finding a ticket that he believes is the winning one, Fitzhugh tries to cut a deal with a giant, Moley.

A giant has been framed for a murder he didn't commit and now awaits execution for the crime. Steve overhears the real murderers discussing their crime shortly after they have attacked him. He vows to find a way of freeing the innocent man and seeing that justice is done.

A giant scientist has created a super android that has gone awry and wrecked a lab, killing a giant policeman in the process. Its creator needs the help of the little people to correct its flaws, and with Mark as prisoner it looks like he will get the help he needs.