Two people with two very different missions cross paths. One, an assassin hell-bent on attaining revenge for the murders of the two people who meant the most to her, and the life she was forced to live as a result. The other, a top agent for S.H.I.E.L.D. that has been assigned to gather intel on said assassin, which would eventually lead to her containment and possible manipulation, or even execution. The two soon learn, however, that things don't always go entirely as planned. As one discovers new hidden abilities and attempts to utilize them while beginning to crack under pressure of her next attack, the other falls into a battle with himself about priorities and the feelings neither one of them can deny. When war is declared on Earth by an unforeseen threat, decisions will be made that will change the course of not only their own lives, but the fate of the entire world.