Sah Gang-kwon was born with powers that label him as a Trace, but such people are feared and discriminated against. He is abandoned by his parents at a young age in a world not only full of prejudice, but also of monsters known as Troubles that kill humans.
Sah Gang-kwon is lucky enough to be then taken in by Han Tae Eun and her family, but there are still Trace that need help and Troubles that need to be destroyed. Their difficult journey to find meaning and acceptance in the world has just begun.