Miss Wormwood takes Calvin to the office to see the principal. Spaceman Spiff is captured and is being taken for torture. He knows the aliens are after the formula to the atomic napalm neutralizer. Spiff springs into action. The principal asks Miss Wormwood why Calvin is eating his hall pass.

Spiff is being pursued. His hyper-freem drive fails. A frap ray nearly misses. Finally, Spiff is hit. He's going down and wonders if he'll make it. As Calvin lands on the ground after coming down the slide, he kisses the sweet ground. Miss Wormwood thinks maybe Calvin should play on the swings instead.

Calvin and Hobbes are outside at night looking for UFO's. Calvin tells Hobbes to keep watching the moon since aliens like to sneak up from behind it. Mom comes up behind them and yells for Calvin to get back into bed. Calvin says that mothers, on the other hand, sneak up behind the pachysandra patch.

Spaceman Spiff is trying to outrun aliens. He shifts into reverse. As the aliens pass, Spiff shifts to forward and chases the aliens. The aliens turn around, so Spiff shifts back into reverse. Calvin, riding in a swing, feels he's getting sick.

Calvin and Hobbes are looking into the evening skies with binoculars. Calvin asks if Hobbes has seen any UFO's yet. Calvin tells him to keep his eyes peeled, that they'll land sooner or later. Hobbes asks what they'll do when the aliens land. Calvin will try to sell Mom and Dad into slavery in exchange for a star cruiser.

Calvin runs into the house telling Mom aliens landed in the back yard and want to talk with her. He offers to guard the cookies while she goes out. He tells her to hurry. Mom asks Calvin how dumb he thinks she is.

Dad asks Calvin what he was doing. Calvin tells him he was looking for dental floss and the handle blew sky high by itself. He changes his story to Hobbes playing around with Dad's tools. Calvin tried to stop Hobbes, but he wouldn't listen. Dad gives Calvin one more try. Calvin tells him big, bug-eyed monsters from Pluto did it and made him swear not to tell.

Susie asks if Calvin brought something for show and tell. Calvin says yes. He brought some charred rocks and ashes from his back yard. He says it's dramatic proof UFO's landed near his house. Their retro rockets burned solid rock into a fragile gray dust cube. Susie looks at it. She says it's an old charcoal briquette. Calvin says as they speak, aliens are infiltrating the highest levels of our government.

Mom tells Calvin to eat his dinner. Spaceman Spiff is held over a pit of putrid pasta. Our hero's mind races furiously. The aliens say that he's had his chance. Let's make him eat. Calvin looks surprised, points behind Mom and Dad, and tells them to look behind them. When they look, Calvin runs off. One alien says the human scum has escaped. The other says tomorrow morning, he'll have cold manicotti for breakfast.

Calvin runs up to Dad, telling him aliens just landed in their back yard. Dad asks what they look like. Calvin tells him like baked potatoes with laser guns. Dad asks if they said what they wanted. Calvin replies they want ten dollars. Dad says he bets they do. Calvin offers that since Dad is so busy, he could give the money to Calvin and he'll take it over to them.

Calvin has dug a message into his yard. It asks aliens to come as they are. They're welcome. Hobbes asks what Calvin will do when his parents see this. Calvin hopes to be halfway to the next galaxy by then.

Calvin asks Dad why old photographs are black and white. He asks if they didn't have color film back then. Dad tells him they did, but the world was black and white then. He says the world didn't turn color until the 1930's. Calvin says that's weird. Dad says truth is stranger than fiction. Calvin then asks why old paintings are in color. If the world was black and white, wouldn't artists have painted it that way? Dad says a lot of great artists were insane. Calvin asks how they could have painted in color. Their paints would have been shades of gray. Dad says the paints turned colors like everything else did in the '30s. Calvin then asks why old black and white photos didn't turn color. Dad says because they were color pictures of black and white. Later, Calvin tells Hobbes the world is a complicated place. Hobbes says whenever it seems that way, he takes a nap in a tree and waits for dinner.

Calvin gets dressed and walks out the door. He trips on a rock and falls through the sky. He wakes up. He gets out of bed, gets dressed, goes out the door, and falls through the sky. He wakes up. He hears Mom call to him, asking if he's getting up.

Mom tells Calvin he'd better go to bed. Calvin wants to read a little more. Mom says they don't want him to get too smart. Calvin is puzzled. Dad explains that if Calvin were smarter, he might realize...his parents are really bug-eyed aliens from Neptune! They rip their masks off, and Calvin runs away. They grab him, get batter ready, and dunk him. They say there's nothing like a fresh batch of earth boy waffles. Calvin wakes up. He says he wasn't asleep and isn't tired. As Mom and Dad carry Calvin to bed, Mom notices Calvin's face was pushed into Dad's leg so hard, it left corduroy lines.

Spaceman Spiff is marooned on the most distant planet in the galaxy. There's no hope of rescue from this bleak world. Spiff tries to repair his disabled spacecraft. CRACK! There's a fly ball to left field. Calvin says there is a commotion on the horizon. Aliens! Calvin says Spiff grabs his blaster.

Calvin sits at his desk with teeth gritted. He says Spiff is being held prisoner by hideous aliens. He wonders what they want with him. Spiff is called before the alien potentate. It becomes clear Spiff is going to be sacrificed....to appease the evil god they call "Nollij". Miss Wormwood tells Calvin to go to the blackboard.

Spiff escapes. The smelly corridors of the fortress are deserted. All the aliens had gathered for the spectacle of our hero's demise. The space explorer makes it to the planet surface, but the alien queen is in pursuit. Miss Wormwood yells for Calvin to come back to the room. Spiff jumps into his spacecraft and blasts off. He's safe!

Calvin stands in front of the class and asks if UFO's are real. He holds up pictures while asking if the amateur photographer got pictures of a sinister alien spaceship and the grim results of a close encounter. Or are they an elaborate hoax? He implores the class to listen to the space alien expert speculate on their hideous biology and their horrifying weaponry. All this and more on Calvin's show and tell coming up next. Miss Wormwood asks Calvin to come over to her.

Spaceman Spiff crashes on Planet Plootarg. He sets off in search of a service station. He sees the Zarches have followed him to the planet's surface to finish him off. The planet's soft, granular ground makes him easy to track. He runs backwards, so his tracks show him going the opposite direction. By continuing past a hiding place and doubling back, Spiff fools the aliens. Calvin, up in a tree, looks down at Mom and Dad. They're yelling that it's time to go in. Dad says he knows Calvin went this way, and that they'll find him.

In rhyme, Calvin is lying in the snow, making an angel. He sees a UFO. The aliens snag Calvin with a hook on his overcoat and hoist him aboard. He tries to fight away, but it's no use. The tie him up and wired his cranium to a suction cup. Current courses across his cerebellum, coaxing things from his brain tissue he wouldn't tell them. All the math he ever learned were removed in this operation. Calvin tells Miss Wormwood his escape was an adventure, but suffice to say, he cannot add, so she should ask some other kid.

Calvin feels rumbling. He looks outside to see brontosauruses walking past his house. He hops on the head of one and rides off. Calvin, with his stick horse, tells Mom he never gets to do anything really fun. Mom tells him that if he's bored, he can clean his room.

Calvin, the commercial pilot, decides to see the Grand Canyon...up close. The jet flies into the canyon. Tourists on the rim wave at Calvin's screaming passengers. After pulling out, Calvin says everyone will be glad later that Calvin took the scenic detour. In the car's back seat, Calvin says if he was driving that's where they would go. Mom says Calvin's not driving, and Arizona is not on the way to the grocery store.

In poem form, aliens come, drain the ocean, suck up the clouds and air. People cry for the aliens to stop. The aliens reply that while they're sorry to learn the people will soon be dead, they prefer their extinction to the loss of the aliens' job. Calvin shows Hobbes his science fiction story. He asks if it's too far-fetched. Hobbes says it's not enough, really.

Calvin is pulled into a flying saucer. The aliens replace Calvin with a robot. The robot steals cookies, breaks a lamp, and throws away schoolbooks, all in front of Mom. Calvin tries to explain it to Mom, but she takes him to bed. Calvin looks at the stars.

Spaceman Spiff is pursued by hostile aliens. Spiff dives toward the mysterious world below. The aliens are still on his trail. He flies through a tight arch, hoping the aliens will crash as they follow. Calvin is under a table, with Mom grabbing at his feet. Calvin says the ol' battleship is surprisingly maneuverable. Mom says Calvin is going to bed if she has to chase him all night.

Spaceman Spiff hops out of his craft. There is indication of aliens. He crouches behind a boulder listening to aliens talk about him. He bursts into the open, shooting his death ray blaster. He yells he'll give the aliens something to talk about. Calvin has shot rubber-tipped darts at Mom, Dad, and their guests. Mom chases Calvin. Later in bed, Calvin says Spiff reflects on his miscalculation. He'll revisit the planet, this time with more ammo.

A Zokk circles above a planet where Spaceman Spiff's spacecraft has crashed. Spiff crawls across the sun-baked land. An alien comes over, tells him to put on sun screen and wear a hat if he's going to be outside. The alien walks off telling Spiff to have some common sense. Mom tells Calvin not to give him that look. Spiff survives, fixes his ship, and goes to find a more temperate climate with fewer aliens.

Calvin says a snowman looks unoriginal. He walks on to see one with female features. Calvin says provoking a reaction isn't the same thing as saying something important. He critiques a snowman family he sees. Calvin tells Hobbes it's hard being the sole guardian of high culture as he makes a snow scene. Hobbes says talent like theirs carries enormous responsibilities. They have made a snow UFO with two snow aliens. A snowman lies decapitated as they add to the scene.

Calvin sees a door he doesn't remember. Something looking like Mom opens the door and gives Calvin some breakfast. He retreats, saying it's not his Mom. It says it is and says to eat his oatmeal. Calvin says this isn't his house, and she's not his Mom. He looks out the window to see a cage. He's in a lab, with giant aliens. One has a puppet of Mom on his hand. Calvin says they're trying to get him to imprint on his own species before they return him to the wild. The aliens complain about a loss of their funding since Calvin is on to them. Calvin wakes up. At breakfast, Mom gives him some oatmeal. He demands she prove she's his Mom.

Two aliens come out of their spacecraft and ask to see the supreme earthling potentate. Calvin says they're speaking to him. One of the aliens says he chose the landing site. Kudos to navigator Nebular.

The aliens are taking over the world. Calvin asks why. The aliens reply earth is prime real estate. Calvin says he never thought of that. One alien says there is charm, atmosphere, and a quiet galaxy. Hobbes says the atmosphere needs cleaning. The other alien says it's a good fixer upper.

Calvin says he can't let them come in and take over the planet. The aliens tell him to prepare for war. Calvin offers to trade the earth for fifty alien tree leaves. One alien whispers the primitive fools must use leaves for currency. It's a deal. Calvin says he needs them by 8:00 tonight, properly identified and labeled. The aliens race off, saying their leader will be most pleased.

Hobbes asks Calvin if he's trading earth for fifty alien tree leaves. Calvin says he'll have the coolest project in class. Plus, he doesn't have to waste any more time on gathering his own leaves. They can goof off all day. Hobbes says then the aliens take over the earth. Calvin replies it isn't like the grownups have done such a bang-up job.

As they play, Hobbes says it's almost bedtime, and the aliens haven't returned with the leaves. Calvin says it's a long trip. Hobbes asks what happens if they don't show up. Calvin says they told him they would. Hobbes wonders if they got lost. Calvin tells him their superior technology prevents them getting lost. Hobbes says it's a big universe. Calvin offers to turn on more lights.

Calvin says the aliens haven't shown up. He bets the aliens got back to their planet and procrastinated. He bets they have no respect for deadlines. He bets they put it off and are doing a lousy job at the last second. Hobbes rolls his eyes and wonders how anyone could be so irresponsible. Calvin says if they aren't there in five minutes, he's not handing over the earth.

Hobbes sees headlights over the trees. Calvin thinks it's the aliens. He goes to collect his leaves. Dad sees Calvin outside collecting leaves in his pajamas. Dad has a flashlight. He tells Calvin to get in bed. Calvin says space aliens left the leaves for him.

Susie asks Calvin if he was up late doing the leaf collection. Calvin tells her his leaves are from another planet. Susie looks at them and says he took fifty maple leaves and cut them into weird shapes. Calvin informs Susie that aliens now own the earth and he told them girls make good zoo exhibits.

Calvin says the teacher didn't believe his leaves were from an alien planet. She told Calvin it was obvious he did it last night and make a mockery of the assignment. Calvin grabs some leaves and tells Hobbes the teacher won't admit it was a pointless project. He asks who cares about leaves. He calls it useless knowledge. Hobbes tells Calvin he's holding poison sumac. Calvin asks what makes Hobbes say that.

Calvin looks out the window to see snow. He thinks it will be perfect sledding weather. The doorbell rings. It's the aliens Calvin sold the planet to for fifty alien tree leaves. They asks what's wrong with the planet he sold.

The aliens complain the cold white glop covers them and freezes their innards. Calvin says it's snow. They get it every winter. The aliens complain Calvin didn't tell them about that. He replies that they didn't ask. They say they were overcharged. Calvin tells them "let the buyer beware". The aliens walk off complaining that he's a dishonorable potentate. They demand he bring the planet up to code.

Mom asks who's at the door. Calvin tells her it's the Girl Scouts. He whisks the aliens outside. He tells them he'll see what he can do about fixing the climate. Mom asks where the Girl Scouts went. Calvin says they had to earn a merit badge.

Calvin tells Hobbes the aliens claim he sold a defective planet. Hobbes suggests offering a refund. Calvin threw away the leaf collection when it got a bad grade. Hobbes thinks they should help them stay warm. Calvin says they don't have arms. They'd need huge socks. Hobbes starts to take down their Christmas stockings from the fireplace. Calvin thinks that's a bad idea.

Hobbes puts the Christmas stockings on the aliens. They thank the earth leader and leave. Calvin complains Santa can't fill them with loot. Hobbes is sure that Santa knows they did a good thing, and things will work out. Calvin realizes he did do something good. He's thinking jackpot now. Hobbes says Calvin's selflessness is the hope of the season.