The Micronauts and Ant-Man has to protect humans from an army of mutated insects.
Complete summary (with spoilers)
On Earth, in the Odd John’s barn, the Endeavor, severely damaged, lays down on the floor. Some minutes before, the insect-fanatic known as Odd John had shot the spacecraft with his shotgun and had stunned Commander Rann with his spray. Hidden behind the spacecraft, the last conscious Micronaut, Marionette, watches her enemy ready to pin the few inch tall Arcturus Rann. Refusing to let her love die, Marionette uses her extraordinary and long-time-trained agility to jump on a hammer put on the side of a table and lever it right into the human head. Knocked out, this one fall heavily in the middle of his strange devices, destroying them. After this success, it’s easy for the Micronauts, back to consciousness, to bond Odd John with a huge chain. Unfortunately, his insect army is already traveling to the nearest food-market and their master cannot call them back after the destruction of his communication device.
In the nearby town, Ant-Man, informed of the coming of the strange insect army by his ants, tries to intercept it before it enters in the Food World Market. He attacks their leader, Bug, but the mutated Micronaut kills the ant he is riding. Thrown down on the street, Scott Lang can only watch the Endeavor, hardy repaired, carrying the Micronauts in the middle of the battle. In the supermarket, Bug hurts a clerk and starts a panic among the customers. Fortunately, Marionette uses one of the thorium cannon of the spacecraft and breaks the market’s door-glasses, permitting the humans to fly. Then, the princess, the Commander Rann, Acroyear and attack the mutated insects of Odd John, propelled by space-gliders.
Acroyear, trying to reason Bug, comes so close to him that he is shot by his friend. The King of Spartak is thrown in a freezer and is instantly freeze. Bug, insensible to his friend fate, also uses his rocket launcher against Rann and Mari. The two lovers, straight shot, lose consciousness and fall in a garbage box which is immediately thrown in a leaving truck. Microtron, in order to help his friends in bad situation, leaves the Endeavor (and Biotron) with the space-station. Then, he takes onboard who is surrounded by the mutated insects. The two Micronauts also get back Acroyear, still stuck in the freezer.
On his side, Ant-Man comes back in the supermarket’s battle. He fights against a mutated flying ant which succeeds to catch him in his mandibles. In the fight, the insect pierces a gas container on the belt of the hero and, strangely, the escaping Pym shrinking gas erase the mutating effect of Odd John’s science. The hazard has permit to Scott Lang to find a way to defeat the Odd John’s army. Relieved of his opponent who is come back to a harmless ant, he climbs to a conditional air vent and, using the air movement, projects his reducing gas all around the Supermarket. Under the gas effect, the entire army of insects comes back to a normal form.
Like them, Bug leaves his mutated form and fall on the ground and soon, Acroyear and Microtron, onboard the astrostation, rescue him. However, the Micronauts have no time to celebrate and fly from the supermarket. In another part of the building, Ant-Man comes onboard the Endeavor, severely damaged by the mutated insects and encounters Biotron. The android tells him about the story of the Micronauts and explain that he has to repair (one more time) the spacecraft. However, he can bring him in the Odd John’s barn and explains to the human hero the plan of the insect fanatic. It will be easy for Scott to later bring the villain to jail later even if he promises to Biotron to keep the secret about the Micronauts.
The victory belongs to the Micronauts but the situation is still bad. Biotron has to repair the Endeavor and especially the damaged communication system. Microtron, Acroyear and have to find a way back to their friends. And Rann and Mari are still stunned, prisoners of a garbage truck which is transporting them far of their teammates.