The Harbinger

The Harbinger is Graham Leslie's first novella, a breakneck science fiction story where humanity has reached out to colonize the solar system. A hundred years after leaving the solar system to start a new human civilization, a generation ship unexpectedly returns to known space. When a washed-up engineer alone on a Ganymedian transport vessel finds himself involved in the return of the ship and the destruction of a budding colony on Rhea, a moon of Saturn, what he discovers exposes a threat unlike anything else and puts the survival of humanity at risk.