Erin has had a special gift since childhood: she can see the color of every soul—red for good, black for evil. At six, she rejects being adopted by the glamorous but black-souled Monicas and chooses to be adopted by the plain Helens, whose souls glow red. Their son Daniel cannot walk, so Erin willingly becomes his little servant. Years later, the girl the Monicas believe is their biological daughter appears, envies Erin, and targets her. Erin repeatedly sees through their plots and protects her family. She also learns that she is the Monicas' biological daughter, deliberately switched at birth. Faced with her birth parents' remorse and wealth, Erin chooses the kind family that raised her, using her gift to protect those who truly love her.
