Well, first a little bit of background story, the 5 main characters, (Brian, Hailey, Jen, Matt, and Karen) are all siblings. Their parents died a little bit over a year ago after their house was in the process of being robbed. The robber shot them, was arrested and sent to prison for a life sentence. Brian and Hailey were left in charge of their 3 siblings.

After a year, Brian and Hailey finally bottle up the courage to go through their parents personal belongings. Their father, being a scientist, had a lot of experiment information in there, including a bottle that had never been opened. The bottle read, "Immunity Formula." Brian and Hailey knew that their father was a trusted scientist and brought the liquid downstairs into the kitchen. They sat at the table, wondering if they should drink it.

Finally, they agreed.