In the late 21st Century, with Earth wracked by climate change and political upheaval, an ambitious private foundation launches a starship to find a new world. Aboard Aeon are Catharin Gault, an idealistic astronaut-physician, and scientist-passenger Joseph Devreze, a molecular biologist as brilliant as he is irresponsible. He has his own hidden motives for fleeing old Earth. Things begin to go amiss while everyone is still in the cold suspended animation called cryostasis, on the long journey through interstellar space. Programmed to search for a planet with a large moon—the only way to guarantee stable seasons, tides and an Earthlike ecosystem after terraforming—the starship finds a destination better than Catharin ever dared hope for: two Earth-sized planets locked in orbit around each other. Planet Green has abundant plant life and a puzzling lack of large animals. Planet Blue is an oceanic world covered with hurricanes. The green planet with its bright blue moon seems like a perfect stage for the drama of civilization to begin anew and turn out better this time. But the journey took far longer than anyone anticipated, and a millennium of cryostasis exacted a heavy price: insidious molecular damage. Now Catharin must rely on the untrustworthy maverick Joseph Devreze to help her save humankind on Planet Green. Their mutual attraction ratchets up even as their conflict escalates. Together Catharin and Joe must decide how they can face, and embrace, a future at odds with Aeon’s planned mission and their own expectations. Meanwhile the mystery of the Hurricane Moon looms over them all. And so the season of crisis begins.

This is a sequel to two earlier books. Hurricane Moon told the story of the immense journey of the exploration starship Aeon and how Aeon’s astronauts discovered mild and mysterious Planet Green with its hurricane-covered ocean moon. Then the season of crisis began. Aeon’s engineers had to overcome damage to the ship. Scientists, including some who had not expected to be revived from cryostasis for what they now had to do, overcame terraforming hurdles and repaired the human genes damaged by long star flight. Some people found unexpected love amid the challenges they faced and some encountered profound spiritual mystery as they laid the foundation for a human future on Planet Green. In Downfall Tide, the brave beginning came to a brutal end. War waged by an inhuman interstellar empire brushed Planet Green. The colony was destroyed. The first generation of colonists managed to send their children away in Aeon to a safer haven, stars away. Now Aeon has reached yet another world—one with a human colony already in place but badly in need of the terraforming resources that Aeon brings. In a new future complicated by the likelihood that the inhuman empire still exists, Aeon needs powerful allies. When an ambassador from the stargoing city-state Avendis offers diplomatic relations with Aeon, young Captain John Mark Josephson sees a golden opportunity. He sends a delegation to accompany her to Avendis in her private starship with its reclusive Captain. Aeon’s delegates are Nathaniel Foster, the young pilot and commander of the interplanetary shuttle Lodestar; Hardin Tucker, who had been a veteran diplomat on Earth; Lodestar’s fierce and loyal First Officer, Anastasia Steed—and Lodestar itself for show and tell. Their mandate is to learn how far to to trust the Avendisans and decide how much of Aeon’s past to reveal to them. On the way to Avendis the diplomatic mission goes astray in the Starcross Nebula. The Avendisans and the delegates from Aeon find themselves lost in a strange and dangerous space. And everyone else looks to Nathaniel for leadership. This sets the stage for Nathaniel’s unplanned coming of age. With just a handful of people of wildly different talents and temperaments and some space technology from two different eras to work with, Nathaniel has to deal with monstrous enemies, unfathomable friends, unexpected aliens—and the long cold shadows of the past.