Kim Yoonsung was a regular guy living a happy life with his family. That is until he discovers he is a "Trace," a class of mutant humans with special abilities who emerged to fight the mysterious monsters known as "Troubles," who threaten Earth. Shunned by ordinary humans, many Traces live in hiding. That's what Yoonsung intended to do, but when his family is suddenly taken from him, he is forced to team up with a wild crew of Traces to find them. Little does he know what "troubles" lie ahead.