Aliens and their Guardians are hiding on Earth from intergalactic bounty hunters. They can only be killed in numerical order, and Number Four is next on the list. This is his story.

Jerry and Rachel are two strangers thrown together by a mysterious phone call from a woman they have never met. Threatening their lives and family, she pushes Jerry and Rachel into a series of increasingly dangerous situations, using the technology of everyday life to track and control their every move.

Xander Cage is left for dead after an incident, though he secretly returns to action for a new, tough assignment with his handler Augustus Gibbons.