Taken from the wiki page... The story set in the contemporary South Korea. Some 30 years ago, unidentified creatures appeared out of nowhere and have attacked people. They have caused massive destruction wherever they go. The monsters are called "Trouble"s, and get the world have fallen into chaos. Along with the first appearance of the "Trouble"s, some number of humans were born with or acquired supernatural abilities. These mutants called "Trace"s are the only ones who can fight the "Trouble"s. The "Trace" are also considered freaks and generally shunned by the community because some of them misused the powers for their own interest. The plot revolves around two main characters. Sa Ghang Gwon, a high school student born as a "Trace" who attempts to hide his ability. The other is Kim Yun Seong, who acquired his "Trace" abilities during his early 30's.