Winter World

A new ice age... and a shocking discovery...
will change humanity forever.

From the Wall Street Journal bestselling author of Departure, Pandemic, and The Atlantis Gene comes a spellbinding sci-fi thriller about a team of scientists racing to stop a new ice age and save humanity from extinction.

* Longlisted for the Wilbur Smith Award for best published novel. *


In the near future, a new ice age has begun.

Humanity stands on the brink of extinction.

Desperate for answers, scientists send probes into the solar system to take readings. Near Mars, they identify a mysterious object drifting toward the Sun. Is it the cause of the ice age? Or could it be humanity’s only hope of survival?

With time running out, NASA launches a mission to make contact. But the object isn’t what anyone thought. In the dark of space, alone, the team makes a discovery that will change the course of human history—and possibly end it.


Filled with real science, Winter World will forever change the way you look at our planet and humanity’s future. Its flawless pacing will keep you up late turning the pages until the final, mind-blowing revelation at the end—a twist you’ll never see coming.


Praise for A.G. Riddle

“...reads like a superior collaboration between Dan Brown and Michael Crichton.”
—The Guardian on Pandemic

“I finished the book fast because I just couldn’t wait...”
—WIRED GeekDad on Departure

“This is apocalyptic sci-fi at its best.”
—Daily Mail on The Solar War


An Extended Look at Winter World

Each month, Earth grows colder.

Snow falls in summer. Glaciers trample cities across North America, Europe, and Asia. The new ice age shows no signs of stopping.

Chaos erupts.

Around the world, people abandon their homes and flock to regions where they can survive. Nations prepare to go to war for the world’s last habitable zones.

Scientists search the cause of the new ice age. They send probes into the solar system to collect readings. Near Mars, a probe finds a mysterious object, drifting toward the Sun. Is it responsible for the new ice age? Or is it merely an observer? Or neither? Could it be a relic from a long-extinct civilization? One thing is certain: investigating the object is humanity’s best hope of survival.

As the ice age claims more lives and the world slides into anarchy, an international consortium launches a mission into space to make contact. But the first contact mission doesn’t go as planned. What the crew discovers out there is beyond anyone’s imagination.

Two members of the first contact mission may hold the keys to humanity’s salvation.

Dr. Emma Matthews is the commander aboard the International Space Station. For months, she has watched the world below freeze and civilization unravel. The headlines tell only half of the story. The messages from her sister tell the rest, of a world witnessing mass migrations, fighting for survival, struggling to provide a future for their children. When a catastrophe strikes the ISS, Emma faces her own fight for survival.

Dr. James Sinclair is one of the greatest scientists alive. A mind before his time. Years ago, he invented something with the potential to change the world—an invention that would upset the balance of power in the world forever. Fearing that change, his enemies sent him to prison for a crime he didn’t commit. But with humanity’s future at stake, NASA asks him to join the first contact mission. His expertise is vital to the mission’s success—and to saving Emma. With the clock ticking down to humanity’s final days on Earth, James makes a decision that will change his life forever and may determine the fate of the entire human race.

Available in Kindle eBook, Audible audiobook, print, and Kindle Unlimited.