In Argentina, Elihas Starr researched quantum energy and built Quantum Tunnel. However, experiment went wrong, his daughter Ava Starr tried to run to her father to ensure he didn't die alone, but the tunnel ruptured before she reached him, killing her father and mother and inundating her with quantum energy. When rescue crews arrived, they were unable to touch her as she had become intangible from the accident.
While working on S.H.I.E.L.D., Bill Foster was assigned to investigate quantum anomaly in Argentina. Then he found Starr and took her from the shelter to help her.