When Timmy finds his toy rocket, he imagines that he and Brushbrush are astronauts in space. Timmy and Brushbrush head to the planet Shmengee to liberate a space station from the Cavity Goon and Ms. Sweety.
The radio wakes up Timmy and Brushbrush to remind them that it's Saturday morning and it means that it is time for wacky cartoons. Timmy wakes up Brushbrush to remind him that its saturday morning. They both rush down to the stairs to watch Saturday morning cartoons, but none of it is good either way. Timmy mentions that saturday morning isn't that very exciting when Brushbrush pushes a chest of toys for them to play with. Timmy plays with a fire engine and imagines that he's a firefighter and pretends that he's putting out a big toaster fire. Timmy finds an airplane for them to pretend that he and Brushbrush are really flying on an airplane, that is until it lands on a pillow. Timmy loves playing with his favorite toys, that he starts singing a song about how he loves playing with toys. Afterwards, Brushbrush reminds Timmy that some of the toys are borrowed from other characters like how he borrowed Johnny Paste's airplane and Sidney Cyclops's ship, so he decides to play with Sidney's ship until he can return it. That is until he found his rocket, turning out that he did borrow it and that he's going to give it back after this important space mission. He and Brushbrush imagine that they're really inside the rocket ship and leaving Flossmore Valley and start heading out into space. Bubbles is seen broadcast via Timmy's monitor giving them an important space mission. Timmy commands that he can't turn down a mission just because its dangerous and there's a chance that he might be late for dinner, all except any mission that requires courage and bravery, because he's Commander Timmy and he has his trusty Brushbrush by his side. Later, the Cavity Goon appears on the monitor to tell Timmy that he and Ms. Sweety have taken control on the new space station on the Planet Shmengee. Its up to Commander Timmy to save the planet Shmengee.
Timmy and Brushbrush are still soaring in space when they see a flying hot dog in the way, but the hot dog passes. Timmy wonders where the planet Shmengee is, so he decides to grab a map to find the planet Shmengee but finds out that the map has been all messed up. He decides to contact mission control. Bubbles appears on the monitor again, Timmy tells her that they're lost in space, but Bubbles tells Timmy that he's forgotten his planets, but Timmy remembers Earth, so Bubbles sings a song about the planets around the galaxy to Timmy and Brushbrush. Bubbles tells Timmy that he's ready for a mission to the Planet Shmengee to return it back from the Goon and Sweety. Timmy gives out another speech that he's going through dangerous space debris and so will his brave co-pilot Brushbrush. Bubbles gives advice to travel to the planet Shmengee by telling him to go all the way to Neptune and then he'll see three asteroids on the left and then turns right, and then he'll go to pluto but doesn't turn but just goes straight until he leaves the solar system when he arrives to the fourth planet on the left. Timmy and Brushbrush travel to the planet Shmengee, and when they arrive down the the stolen planet, they meet Sidney Cyclops (as ambassador of the planet Shmengee) as he greets him to the planet Shmengee and makes sure that his stay there will be the most enjoyable one. He does his own hand shake by making weird noises and moves. Timmy tells Sidney that there's big trouble in the planet Shmengee which is Sidney's fault, which would be him trying to let the Goon borrow the telephone, but tricks him by locking him out of the space station and not letting him back in. The Goon welcomes the travelers and ambassador to the Goon's planet. Timmy mentions that the Goon is roughest toughest baddest bad guy he can ever run into. Timmy and Sidney decide to plan on what they're gonna do to get the Goon and Sweety out of the space station. They decided to do the ice-cream-man-plan. When they're trying to sell ice cream, Sweety sees the ice cream vendor and starts going ga-ga, until the Goon gives her a lollypop to snap out of it. The plan failed. The good guys start doing the Sugar-World-Plan, by playing a board game of Sugar-World. Meanwhile, the Goon sees that they're playing the game and says that it is his favorite game in the whole galaxy, so that he can come out and play one teensy weensie little game and then he'll win, but Sweety won't let him because it is a trap to let them out of the space station and tells him that no one plays Sugar-World anymore. The plan failed too. Timmy and Sidney try to get help by having Timmy talk to mission control on how they're stuck on the planet Shmengee and that they have failed on two attempts to get the two bad guys out of the space station, so Bubbles reminds Timmy that he needs Plan B: A Bigger Better Bolder Plan, but the Goon and Sweety appear on the walkie-talkie to remind him that he needs more than plan B to stop them and tells the good guys that they should try plan C: Cookies, Candy and Cupcakes. Timmy thinks that the mission is going to be harder than he thought.
Timmy likes Plan B better, so he, Sidney, and Brushbrush decide to develope plan B to try to get the bad guys out of the space station by using tools like blueprints. Meanwhile, the Goon and Sweety are throwing trash all over the planet until Timmy, Brushbrush, and Sidney arrive to the space station all ready for Plan B. Timmy pushes the button and gets everyone swapped from place to place three times wrong (one is all the Muppets on the planet Shmengee outside of the spacestation) until they get it right and the Goon and Sweety are out of the space station for good, and Timmy, Sidney, and Brushbrush have the space station and tell the bad guys that they need to keep Shmengee beautiful. Timmy tells Bubbles via walkie-talkie that plan B worked and Bubbles tells Timmy to return to Flossmore Valley, but Timmy has one more thing left to do on the Planet Shmengee. Meanwhile while the Goon and Sweety are cleaning up the mess they've made, the Goon wants Sweety to jump, but Sweety declines, but the Goon wants her to do it anyways, so she did. The goon lied. Timmy decides to play ball on the planet Shmengee to test the laws of gravity, by hitting the ball all over the galaxy and goes somewhere but Timmy wonders where its going. Back on earth, Walter Crunelemuffin reports that the good guys have saved the day and the Planet Shmengee. Crunelemuffin signs off from Timmy's imagination wrapping up the report of the National Return Borrowed Toys Day. Timmy and Brushbrush return to their home safe and sound, so they decided to return these toys back to their respective owners, starting with Bubbles' rocket, Sidney's ship and then Paste's airplane, and then the two of them can play some T-ball. Meanwhile, the baseball that Timmy hitted while he was at the planet Shmengee landed on Timmy's couch.
- Kevin Carlson as Timmy the Tooth
- Bruce Lanoil as Sidney Cyclops, Ms. Sweety, Announcer #1
- Cheryl Blaylock as Bubbles
- James Murray as the Cavity Goon, Announcer #2, Unseen TV Characters
- Christine Papalexis as Nicki
- Phil Baron as Walter Crunelemuffin
- Dina Fraboni as Irene
Main Characters (speaking):
- Timmy the Tooth, Sidney Cyclops, The Cavity Goon, Ms. Sweety, Bubbles Gum, Walter Crunelemuffin, Nicki and Irene
Background Characters (non-speaking):
- Bowties Timmy Wears: His Pajamas Bowtie, His Silver Space Bowtie
- Cavity Goon Plots: Taking Over the Space Station on the Planet Shmengee
- Alternate Character Identities: Timmy the Tooth as Commander Timmy; Sidney Cyclops as Ambassador Sidney