While out for a movie day, a mysterious Powerpuff-like girl saves Blossom, Bubbles and Buttercup from a villain. The professor reveals that she is Blisstina, or just "Bliss" for short, and his earliest endeavor to create the perfect little girl. However, Bliss's powers became unstable and began combining with her emotions causing explosions whenever she was happy, sad, fearful or angry. Professor thought she was destroyed in their last encounter, when in reality, she had run away to a deserted island to avoid causing any further harm to the Professor. After ten years, Bliss has returned out of homesickness and is quite surprised to find that she now has sisters who are more then welcoming to her. However, Bliss still has trouble with her powers, which could both spell trouble for the city and dampen her relationship with her family.