The episode begins with Gadget putting the finishing touches on the Ranger Rocket. Zipper attempts to launch the rocket himself, but he isn't strong enough. Feeling too small, Zipper flies off. In a junkyard, Professor Nimnul is looking for ugly insects for unknown purposes. Nimnul comes across a bunch of small pill bugs. Realizing their perfect for his plan, he runs to get his growth ray. Zipper arrives at the junkyard and runs into the pill bugs. The bugs are about to gang up on Zipper when Nimnul comes back and zaps the pill bugs-and Zipper-with his growth ray. Zipper flies off as Nimnul scoops the pill bugs into a jar. When Zipper returns to ranger headquarters, the others are surprised to see he seems a little bigger than usual.
With the pill bugs growing at an amazing rate, Nimnul begins to put his plan into action. The pill bugs attempt to consume Nimnuls lair, but with the threat of being returned to normal size, Nimnul is able to keep them in line. Nimnul then begins to fill a tire with helium and it expands to a large size.
Back at ranger headquarters, the rangers are running tests to see why Zipper has grown to such a large size. They hear on the t.v that a group of beings that call themselves space creatures are demanding lots of gold from the city. The military attempts to stop the creatures, but their weapons don't lay a scratch on them. The rangers aren't sure the creatures are aliens as they are wearing junk parts and the leader sounded strangely familiar. The rangers head to city hall (on Zipper's back) to get a closer look.
On the way to city hall, many people see Zipper and assume he is one of the aliens. The police arrive and start shooting at him. The rangers fall off Zipper's back as he ducks into a clothing store. The S.W.A.T team arrives and storms the building, but they find no sign of Zipper (they didn't know he disguised himself and ran out with the crowd). Knowing that he is now too big to fit at ranger headquarters, Zipper goes into hiding until his growing process wears off- if it does.
The rangers fly up to the alien's flying saucer and discover it is made of rubber. When Monty busts open a door, an alarm goes off and the rangers are discovered. The rangers realize Nimnul is behind this, he is using fake aliens to scare the city into giving him gold. Nimnul locks up the ranger's as his "aliens" go to retrieve the gold the city has brought them.
After the last of the gold is loaded on to the fake ship, the leader (Nimnul is doing the talking for him) bids farewell. The rangers escape from their cage and jump up to Nimnul's microphone and try to tell everyone it is a trick, but no one can understand them. Nimnul swats the rangers with a newspaper and they get trapped in it. At a cookie factory, Zipper (who is now a giant) finishes up his meal when he hears a report about the aliens. Everyone believes the strange gibberish to be the alien's native tongue, but Zipper knows what it means- his friends need help.
On board the phony spaceship, the rangers attempt to hide from Nimnul, but run into three of his aliens. Just as they are about to eat the rangers, Nimnul zaps them with his growth ray, shrinking them back to their normal size. When the rangers see the aliens are ordinary pill bugs, they realize what is causing Zipper to grow so big. Nimnul is about to shrink his last alien when there's a loud bang on top of the ship. Nimnul looks out the window and sees Zipper on the roof. Nimnul tries to fly off, but Zipper is blocking his view and he hits the tip of a skyscraper, puncturing the tire and causing the ship to fly out of control. The rangers fall out the door and fold the paper into an airplane to float to the ground. Nimnul bails out of his ship as the tire wraps around Zipper, pinning his wings down and causing to fall as well. The ship, gold, and Zipper crash to earth and Nimnul lands in Zipper's hand. A tank arrives and aims at Zipper. Without his ability to fly, Zipper has no choice but to run. The rangers find Nimnul's growth ray and plan to use it to return Zipper to normal size.
The army chases Zipper up a building. The rangers manage to reach the roof just as a helicopter fires a missile, causing Zipper and Nimnul to fall to earth. The rangers quickly zap Zipper with the growth ray, returning him to normal size. With his wings free, Zipper is able to stay in the air while Nimnul crashes into a sewer. Nobody is sure what just happened. Nimnul climbs out of the sewer and climbs into a car to drive off. Little does he now, his last pill bug was hiding in there, and without his growth ray, Nimnul no longer controls it. The episode ends with the rangers saying that though he is small, Zipper is a big part of the team.