The episode starts with an army general spraying his soldiers for bugs. He then goes to his computer, which tells him that an unidentified force on Earth is draining power, and the officer believes that it’s caused by aliens with a plan to contaminate the military with germs in an attempt to take over the world. He tells the computer to destroy the aliens. The soldiers are then changed into protective suits, and they grab anti-germ weapons, get into helicopters, tanks, submarines, ships and planes and leave.
Meanwhile, Dexter is using a lot of electricity for many inventions in his lab, in order to make facial cream that will make him “both smart and beautiful”. However, the facial cream smells bad, and when Dad walks past Dexter’s room, he tells Dexter that his room is stinky and that he’d better clean it up. Dexter notices that he appears to have neglected the lab’s cleanliness lately, when papers, plants and broken test tubes are on the floor and a rat hops past him. Then his computer warns him of an intruder. Dexter asks her what is intruding, and Computer shows the Army’s vehicles headed towards his house, saying that it is an “unidentified fighting force”. Dexter asks who it is, and she repeats that it is unidentified, making him angry. Dexter then puts on his headphones to listen, and hears crackling sounds and the general telling his soldiers that they’re about to encounter the aliens’ groundbase. This makes Dexter think that aliens are coming, and he runs away, slips on a banana peel and lands in his facial cleanser. When he resurfaces, he is green and screams that his eyes are burning.
The army vehicles approach Dexter’s house. The planes sit above it, and a tank and ship come into his yard. The soldiers jump out of the planes in parachutes and land in Dexter’s lab. They believe Dexter’s cleanser to be soup with chicken in it, and they complain that the lab stinks. They look for the aliens, and Dexter is hiding behind an invention. He believes that the soldiers are aliens, and one of them opens a freezer where Dexter keeps his biologically-engineered jurassic eggs. He believes that the eggs are the aliens’ nest, and one squirts him in the face with green fluid. He runs out, screaming to get the germs off of him. He then throws an explosive into the freezer, and shuts the door before it explodes. This upsets Dexter, and he jumps toward the soldier and kicks him, knocking him down. He is about to beat him up, when the rest of the army crowds around them with their anti-germ weapons. Dexter runs away, and the soldiers chase him, pointing their weapons. Dexter returns to his cleanser, and takes a glob out and throws it at them. It knocks one of them over, and he drops his weapon. He runs away, yelling that it stings. Dexter says that the aliens seem to have an aversion to bad smells, and he then gets an idea. He runs into a part of his lab behind doors that say “KEEP OUT”, and he grabs a large white shining ball, a box of fireworks and a tube from a vacuum. He attaches a large container to a small one with the tube, causing cleanser from the large tube to go into the small one. He attaches the tube to the ball, which is now clear and being used by Dexter as a helmet. (Other than this he is only wearing his underwear and boots, and he is still green.) He attached a firework to each boot, using them like a jet pack. He blasts out and shoots cleanser at three of the soldiers, causing them to scream about the smell. Dexter flies and does this to two more, and then several more. One of the soldiers tells the general over the radio that they are under “severe stink attack” and to pull out as Dexter continues to shoot cleanser at the group. They are all lying on the floor screaming, and Dexter lands and pulls his helmet off, saying “Looks like I’ve defeated them all!” However, one last one shadows over him and says “Not quite!” He points an anti-germ weapon at Dexter and shoots, washing the cleanser off of him.
The shooter turns out to be the general, who then realizes that Dexter is not a filthy alien, but a little boy, and Dexter says that the general is a grown man whose army was defeated by a little boy. The general tells Dexter that he has a point, and tells him that if word gets out that the Navy was defeated by a little boy, they will be the laughing stock of the world, and Dexter agrees. The general asks Dexter to keep it a secret, and Dexter tells him that he will on two conditions: That they keep his lab a secret, and that they clean it. They general agrees, and the next frame shows the lab cleaned and sparkling, and Dexter’s inventions that were broken from the fight repaired. Dexter tells the general that they did an excellent job, and the army then returns to their base for a bath. Dad comes back and tells Dexter that he hopes he remembered to clean his room. Dexter tells him that he did, and the episode ends.