On the planet Mars the king has decided to explore the vast space of the universe and conquer all the planets. When the invasion starts the Martians go to each and every planet battling their armies and destroying each and every one of them. Every time the Martians conquer a planet they drop off thousands of Martians, who are simple families and workers, to start building their kingdom on that planet. Then as the Martians fly back to their planet to refuel and recruit they get ambushed by the Sun Warriors. The Sun Warriors are the soldiers of the god species of the star The Sun. The Sun Warriors obliterated almost all of the Martians leaving no survivors. The king's ship, with ten thousand Martians on board, got away in time, but got its engines hit so they had to have an emergency landing on a nearby planet, that they didn't get to conquer yet, Earth. The king heard about the earthlings being some awesome race, so not to be spotted they put up a special barrier that hid them from the earthlings' technology and also to hide themselves crashing into the mountain next to a city named Moreno Valley.
The Martians, now stuck on Earth, have to find a way to fix their ship and get back to Mars, and then one of the Martians told the king that Moreno Valley is actually a secret military base underground. So the king sees that he can use the earthlings' technology to fix their ship and orders his men to develop a device that disguises themselves as humans and investigate this. As his men spread out and blend in with everybody in schools, shops, malls, restaurants, clubs, etc. they find that nobody knows that Moreno Valley is a secret underground military base. The Martians even kidnapped some people dived into the depths of their brains and found two things: it is a fact that nobody knew about the secret underground base and that humans are mere weaklings they're not some awesome race that every world has been rumoring about. So when the king finds about this appealing news he tells his men to start repairing their equipment to make more weapons for the war that is about to come Humans versus Martians.
Two human years have passed and the Martians are almost ready for the war and the humans just live their lives with no clue in what's going to happen. Before we get into all the action and the killing, the Martian families were given the choice to get out the ship and disguise themselves and blend in with the humans. In the two years some Martian families grew to love the Earth and actually turn from their own race, without their own race knowing. So back to the start of the war, the Martians send out a five devices: four of them go the each of the corners of Moreno Valley and put up a giant barrier so nothing and no one can come in or out and the other cities, states, countries, etc. can't detect what's going on in Moreno Valley. The last device broadcasts a giant image over Moreno Valley showing the Martian king saying "earthlings I the king of Mars have come to destroy you and conquer your world if you dare to resist then we shall go to war!" The humans didn't know what to do and started to freak out. The Martians sent out their first platoon of soldiers and started to attack buildings and homes to show they were serious, but then the Martian families, who turned from their own race, took out their weapons and started to fight back, without showing their true identity. The humans that know the Martian families were surprised but got encouraged to do the same so they got out their guns and weapons out and started to fight back. They then noticed that their weapons didn't work but the Martians families' weapons did so they asked where they can get weapons like that. So all the Martian families around the city came together and told everybody that under Moreno Valley is a secret military base and showed them the way to get in. When the humans saw this base they were so amazed at how all this was just right under their noses then when they were trying to find were the weapons were stored they found a room full of different world weapons. They found out that Mars wasn't the only world that tried to conquer Earth the rest of the planets tried to and Earth won every single one of these wars and kept all the other worlds' weapons and vehicles.
The humans now are fully equipped with Earth and other world weapons and vehicles that the war has now started. When the humans go back up to land they see half of Moreno Valley reduced to scraps angrily the humans charge at the Martians