The Micronauts fight to defend Spartak of the Karza's army.
Complete Summary (with Spoilers)
After desperately crashing his space fighter on the force field of Baron Karza, Arcturus Rann is on the hands of the tyrant of the Microverse, Defending the man she loves, princess Mari engages the fight but she is quickly also captured by the Baron.
Around them, the battle between the fleet of Karza and the Acroyears continues. Bug fights against a Phobos, a giant humanoid war machine but this one explodes, apparently killing the insectoid micronauts and letting Microtron alone in the middle of the space.
On spartak, in the Crystal chamber, Acroyear enters in symbiosis with his home planet. So, first-able, huge rocks fly from the planet, destroying the dog soldier's spacecrafts. Then, when the fleet approach of the ground, the Spartak's mountains rises and hits the spacecrafts. Even the volcanoes throws columns of lava on the assailants. Finally, lead by Acroyear, the planet increases his mass, forcing the Dog soldiers fighters to crash on her and throwing them in huge rifts.
Most of the Karza fleet is destroyed but, motivated by the Karza,'s promises of immortality, the dog soldiers start a surface assault. Showing no mercy, the always numerous minions of Karza kill men, women and children. The remaining Acroyear warriors, led by Cilicia, take refuge in the temple protecting the Crystal Chamber. Even with the might of Spartak, the acroyears warriors were outnumbered and die like flies. The end seem inexorable.
But Celicia want to respect the pact between her planet and his inhabitants. Following by Microtron aspiring to avenge the fallen Micronauts, she leads a mighty counter-attack. The acroyear ferocity, always with the planet support, surprises the Karza soldiers and, after the more epic battle on the surface of Spartak, the Acroyears win. At the end, It's as a victorious and acclaimed king that Acroyear shows himself to his people.
On Homeworld, the situation changes too. Prince Argon and Slug and their underground army have invested the body banks. They release all the prisoners and arm them. Argon also proposes to some riches to join the rebellion against Karza but these one prefer death than betrayed a system who gave them nearly immortality. Outside of the Body Banks, strangely, the dog soldiers doesn't attack. But sooner, the reason of the waiting is revealed: in a thunder strike, the karza spacecraft appeared.
Even if the battle of Spartak was a success, the micronauts's situation is awful. Acroyear, Microtron and Biotron are on Spartak with a few surviving acroyear, Bug is dead and Commander Rann and Marionette are the prisoners of Karza who, certainly, want to re-conquered his body banks.