The Signal is on Earth. The world is being infected. David Bryce returned in a crashed starship, but his mission was unsuccessful. He’s sent to Alaska with his family, but the infection has already begun. When he finds an alien device, he might just be able to change the course of an impossible war. The Signal is hidden somewhere on Earth. The race is on to find it before the invaders do, but an insidious ailment is spreading across the globe, making it difficult to know who to trust. Lennon Baxter leads a Dark Team, hunting the Stalkers as they seek to congregate. But what is their motive? Atlas Donovan is the only man capable of helping the Association, and it’s unclear whether he can trust the enigmatic Dark Leader. He heads to the Amazon jungle to search for the Signal, the fate of the world in his hands.