Harper Cambridge is an agent with Genesis.
Well, she will become one soon after our introduction to her - which itself will come not long after she learns about Genesis in the first place. When she is finally informed about it, she is told it is an FBI project that "recruits and trains the most elite spies, undercover cops, agents, and assassins in the country" and it is so hush-hush that "the President doesn't know it exists".
When we meet her for the first time, she and her twin sister Joanna ('Jo') are 16 years old and deeply concerned about the disappearance of their only parent, their mother, who disappeared four days before. While Jo is anxious to call the police to report her missing, Harper is adamant in her refusal: "No police, you know that". That statement gives a good inkling into the mystery that surrounds this family. The girls' only other family relative they have is their aunt, Veronica, and "even she is reserved and mysterious and won't tell us a thing about our family".
Harper gets her first introduction to existence of 'the Genesis Project' when a handwritten note is left on her doorstep with a cryptic warning the this mysterious project was in danger "and so are you, your sister, and your mother. Your family's past has caught up with us all and none of us will be able to escale what is about to happen". The note warns her "do not trust anyone after reading my letter. If you do, I cannot guarantee your survival in this. Nor my own".
The Cambridge sisters are in a quandry when this unfortunate set of events take place and in no condition to be abandoned. Harper is not old enough to legally drive and Jo suffers badly from multiple sclerosis which is escalating again. They have lived a very sheltered life so far and Harper realizes that she has no idea what it is that her mother did for a living. The mysteries will just get adding up.
Now it is time to introduce Skye. This young lady is also 16 years old but unlike the Cambridge girls, she has no parent. She was living in an orphanage when Genesis came to the facility when she was 13 and pulled her and several others out to go into specialized training. Her specialty was slated to be that of assassin and she has been given a good deal of training over the past 3 years to make her a formidable weapon. Then she broke free.
So now we have Skye and a mystery man known simply as 'D' joining up with Harper to go up against Genesis who may or may not be bad guys after all. Genesis is being challenged as well by a successor organization named Scorpion which may or may not be even worse.
It is all a bit confusing.
But Skye is fun to follow.