When a lone soldier, Cole, arrives with news of Lachlan Agatta's death, all hope seems lost for Catarina. Her father was the world's leading geneticist, and humanity's best hope of beating a devastating virus. Then, hidden beneath Cole's genehacked enhancements she finds a message of hope: Lachlan created a vaccine. Only she can find and decrypt it, if she can unravel the clues he left for her. The closer she gets, the more she finds herself at risk from Cartaxus, a shadowy organization with a stranglehold on the world's genetic tech. But it's too late to turn back. There are three billion lives at stake, two people who can save them, and one final secret that Cat must unlock. A secret that will change everything.