Hydrus Four

Hydrus 4 is the only planet on which the miracle restorative Nucleon can be found. Now, this WOULD be plenty of cause to journey to the planet except for a few middlesome problems.

Specifically, the fact that the planet is inhabited by creepy obsessive zombie mechanoids who guard the Nucleon. Also: the only inhabitants of the planet who are NOT Robo-Zombies live only to warn people of the zombies.