MacKenzie Hollingsworth and her sister, McKenna, have spent the past year adjusting to a new normal after James Vick's organization, Agma, almost ended their lives.

Several law enforcement and national security agencies investigated in the aftermath of Agma's deadly operation, which ultimately came to a violent end. Although the agencies involved initially believed Agma was a small organization built on one man's prejudice and desire for revenge, they soon learned that it was a vast, homegrown terrorist organization with connections throughout the world.

Agma's new leader, JoAnn Vick, worked hard to rebuild the organization after her husband's death, and JoAnn was as cold, calculating, and focused on revenge as her late husband had been. She developed new financial and personnel resources, including a resource for a new bioweapon created in a small lab in the horn of Africa. Because she blamed MacKenzie Hollingsworth for her husband's death, she decided that infecting MacKenzie and McKenna would be the perfect way of deploying the weapon and exacting her revenge.

However, JoAnn is unaware of the growing dissension in Agma's ranks—and she underestimates the resilience of the Hollingsworth sisters.