Kardia is a dark supernatural action-drama about seemingly normal high-school girl Diana, who begins to hear a voice in her head. Scared and nervous, she goes home to tell her mother about it, but blacks out upon arrival, waking up to find her mother has been murdered and a strange woman has a gun to her head.
From then on, Diana's life is anything but normal. She now lives with the woman who took her away at gunpoint named Melissa, and two others like them that tell her she has a unique virus that makes her dangerous, and the world will kill her if she is found.
What Diana doesn't know is that there is more to her than she knows. As she works her way into the hearts of her "family" and becomes increasing attached to Melissa, her safety will be threatened, her concept of reality shattered, and at the end of it all, her greatest enemy may turn out to be herself.