This story takes place in the year 2059. Since the Earth's limited resources have been wasted by the human race, new energy sources had to be found out of the planet.
After several years of investigation, a group of scientists discovered new minerals under the crust of Jupiter moons. Those minerals turned out to be a great energy source, that's why a large scale exploitation was planned from Earth. So the Power Afield Company (P.A.C.) was founded in order to create 5 automatic driller robots called Drilleroids designed to carry out all the work without need of human intervention.
The Drilleroids were sent to Jupiter and started to work successfully. Nevertheless, unexpected troubles came up: there was life under the crust of Jupiter moons... small beings which felt threatened by the presence of the Drilleroids and attacked them causing serious damage.
A space mission manned by a team of experienced astronauts was launched to repair the Drilleroids and equip them with a self-defense system to avoid future attacks. This mission was called J.E.T.P.A.C. (Jupiter Elite Troop Power Afield Company).
They completed their duty and returned to the spaceship willing to return to Earth. Sadly, they found out it had invaded Jupiter's asteroid belt, receiving several serious impacts: the main power generator and the transmission systems were damaged. The team was condemned to die, resting forever around Jupiter's orbit.
Suddenly, they came up with a desperate way to save their lives: to obtain the energy modules from the Drilleroids with the hope they could generate enough power to reactivate the spaceship... but after installing the self-defense systems and not being able to disable them by radio, there is no option but fighting the Drilleroids to snatch their energy modules.