The Infected.

When Cali turned 22, she decided to escape from the mansion where her father kept her locked for ten straight years without knowing the reason and she was forbidden to use any gadgets and from going to the basement. Because of the excessive strictness and unanswered questions, Cali broke the rule and went down the basement and as soon as she opened the basement door, she found a girl who was chained up with bloodstains on her dress. Then she found out that the girl she found was her sister whom she never knew existed. She helped her out only to regret it instantly because it turns out that her sister, Candace, was already infected.