It has been three years since Tristan and Joane have seen each other. The two colleagues fled to opposite sides of the known universe to avoid seeing one another ever again. Unfortunately for them, fate-- and their former employer-- has other ideas.

Twenty-seven planets have gone missing in the past few months with no explanation. When Ahsha, the eccentric and rough-edged scientist who brought the two of them together, winds up disappearing alongside the most recent Vanishing, Tristan and Joane are the only two people in the universe who may have a clue as to what's going on.

Faced with insurmountable odds, unpredictable perils, and a potential conspiracy that could unravel the cosmos, Tristan and Joane have no choice but to band together to find the Vanished Worlds, rescue their former associate, and confront the feelings that drove them apart in the first place...