A group project for Shop class takes a turn for the worse when an old weapon intended for another group of heroes comes around to haunt Tyler and his friends.
Herschel Clay opens his session of Shop Class by noting that scorch marks clean up well if the right solvents are used and they can barely tell there was a succession of explosions in the classroom a few days ago that cost thousands of dollars worth of damage. He then notes that he'd like to keep it that way and moves on to checking the students' homework.
Zodon was assigned to construct a simple laser using a flashlight and binocular lenses. Unfortunately for Zodon, it was confiscated by Miss Kyle. Herschel reminds him to leave future projects in the work area. Victor VonFogg was given a solar-powered calculator and an old floppy drive, and was assigned to merge the two so that the calculator could read floppies. Victor took it upon himself to reconfigure the kit to be able to generate the launch codes for every nuclear arsenal in the USA. Fortunately for the rest of the world, he doesn't have his driver's license and can't make the trip on his own. Tyler was assigned to take apart his arm-mounted grappling unit and reassemble it. Upon test-firing it, Tyler is nearly blown out of his seat from the force of the cable's launch. It turns out Angela helped him soup-up the grappler. Herschel admonishes her to let Tyler do his own work and then moves on to checking her work. For her project she selected a tape deck, a fuel line hose, and an air freshener, using them to construct an air-breather that will provide the user with an hour of pine-scented air. It also happens to act as a flamethrower if the user has a source of fire handy, such as a Zippo, which she has with her. After nearly getting singed, Herschel confiscates the lighter until the end of class and then moves on to Prospero. Prospero apparently selected an old toaster and a Nintendo Entertainment System, which he uses to produce two perfectly toasted slices of bread out of thin air.
Herschel then goes on to note that as this is the third week of shop class they will be starting on group projects, split into two teams. He pairs Zodon and Victor on one team, and Tyler, Angela, and Prospero on the other. He then explains the nature of the project. Each team will be given ten pounds of dilatant compound. They are to create something that exploits its unique properties, but no explosives. He then distributes the compound to the teams and lets them start brainstorming. Angie and Tyler quickly discover that the dilatant compound is what is commonly called Silly Putty. Tyler shows Angie how it can be used to copy newsprint as well as bounce when rolled into a ball. Angie and Prospero quickly come up with a plan to super-charge the silly putty's bounce ability and ask Tyler to meet them topside after class that afternoon.
Tyler meets up with the pair after school and they head for Angie's house. Angie's father ran a junkyard when they lived in St. Louis and when they moved so Angie could attend PS238 he bought a junkyard in the vicinity. Angie gives them the tour of the yard and then takes them to her "mission control" area, which she built from old cars, buses, and planes with Prospero's help. They pile into a small area of the "fort" and then, much to Tyler's surprise, they launch into orbit! Angie and Prospero's makeshift shuttlecraft is designed to fire its rockets in a jerky sequence that makes liftoff a bit rough but masks the noise of the launch by sounding like someone's car stereo with the bass turned all the way up. Angie has also fitted it with air-producing capability as well as a transponder box that she swiped from one of the school's shuttles.
As they reach the proper orbital level Angie has Prospero make ready with a docking line so they can land on a rather ramshackle satellite. In order to dock the line hooks on to a rail on the satellite and causes the shuttle to whip around it, landing on the docking plate. Unfortunately, this causes Tyler to lose his lunch.
Once they have docked and boarded the satellite, Tyler questions its presence in orbit. Angie notes that when she was looking for a place in orbit she found a satellite that was being brought down in a controlled fall, which she took to be a "vacancy" sign. She then started launching her own space junk into the same spot and lashed it together. Prospero has helped her make improvements on the satellite since they met, such as adding a large telescope. Angie has Tyler suit up so he and Prospero can do work on the silly putty outside the space station.
While outside working on the compound, Tyler notices something small and metal heading towards their space station. Angie notes that she's not picking it up on her sensors and has Tyler and Prospero hurry back inside after securing the putty. Once the pair are back inside, Angie explains her plans to Tyler - that they're going to make the putty MEGA-BOUNCE. By adding chemicals to the silly putty they have made its surface strength immeasurably stronger and made the putty itself nearly indestructible. Angie speculates that they might even be able to make it bounce back and hit the moon. As Tyler notes that his parents' defense grid won't like that, the station gets an unwelcome visitor - the metallic item Tyler spotted earlier.
Once the item hits the station's hull, it begins broadcasting a recording - from Doctor VonFogg, Victor's father. The item is an explosive mine that was designed to attach itself to the Union of Justice's satellite when at least three members were on board. The mine has magnetically sealed the hull and is set to detonate in ten minutes.
Tyler questions Angie as to whether or not it was the Union of Justice's satellite that was formerly in the location of her station. She notes that she doesn't know, she just took the spot they left. They bemoan the fact that the hull is sealed and as such they won't be able to remove the mine. Angie is more concerned that she won't get to see the putty do its bounce. This gives Tyler an idea - if they can get the putty to bounce at the right angle, they can use it to knock the mine off of the station when it comes back. Prospero and Angie begin crunching numbers and send Tyler down to the airlock where the launch controls are located - a game boy, duct-taped to the wall. Angie gives Tyler a button sequence to press, and the putty launches towards Earth.
Somewhere in farm country, a farmer is out inspecting his wheat field. He is shocked to see a gigantic pink blob impact on the field, leaving a perfect crop circle. He then runs, yelling for his wife Martha to save the cows, because the aliens are coming! Meanwhile, back on the space station, Tyler paces the floor as Angie and Prospero play with portable game systems. They watch the video of Doctor VonFogg as he gleefully counts down the last twenty seconds of lifetime for the Union of Justice. After he reaches nineteen, the putty impacts with the mine, engulfing it and tearing it off the wing of the space station. As the countdown reaches one, the mine explodes inside the supercharged silly putty, causing it to form a giant pink sphere, much to Angie's delight.
The next day, shop class reconvenes and the threesome explains their project to Herschel. He initially doesn't buy their story, but then uses his contacts in NASA to check up on it. Much to his surprise, they confirm the tale of a giant pink sphere appearing in orbit. He notes to the children that they should turn in their formulas and he will give them an A on the project. He then turns to Zodon and Victor to see what they came up with. Despite their constant arguing, they were able to turn the silly putty into a nanoelastic programmable putty that could have possible evil purposes - if the two could ever agree on what those purposes are. Herschel scratches his head and asks the others if they want to go look for something big and pink in orbit.
Epilogue: Somewhere in farm country, Martha is arguing with her husband Todd. He has set up a stand to charge people for viewing the "alien crop circle", which Martha thinks is a stupid idea. As she storms off to the farmhouse she yells at Todd to tear down the stand and get back to work. Todd sits behind the stand, sulking, when he is surprised by the sound of rockets firing in a bass-drum pattern. Angie and Prospero's shuttle sets down by his stand, and Angie pokes her head out the hatch. At Prospero's insistence, she apologies for the damages to his field and in compensation she gives him three loaves of bread and a jar of peanut butter. Prospero then shoots him with a ping-pong ball from his gun, indicating that he thinks the farmer is an ok guy, and they close the hatch and lift off. Later, Martha is back at Todd's stand. He has amended his pricing to include a sale on Space Peanut-butter sandwiches. Martha is still dubious of the whole thing, and still thinks Todd is a little bit crazy.