To earn a place in galactic society, the astronauts of Sanctuary must give an unknown civilization twenty-seven ideas, a ladder to lift it to the next level… if sabotage or space travel doesn’t kill them first. Yuki needs to replace an arm while covering up previous misdeeds. Mercy navigates a high-risk pregnancy with a sociopathic doctor. Yvette struggles to convince the others that the aliens who provided the ship are not as benevolent as they seem. Their target is Oblivion B4, the fourth moon of a gas giant similar to Jupiter. The moon has a maze of cracks on the surface where life flourishes, earning it the name Labyrinth. More than one maze needs to be threaded if they're going to return to Earth.