He was Kwon Ji Hyuk, a troubled high school flower boy with a band in "Shut Up Flower Boy Band." Then Sung Joon played Suzy's sidekick and devoted bodyguard in "Gu Family Book." Just in case this is not enough Sung Joon for you, this month you can see the actor go back to high school when he plays Yoo Jin, super smart student in the film "Pluto."

The film by director Shin Su Won is set in a private high school attended by the nation's top students. Not only is the school elite but the brightest students also have an exclusive study group there led by Yoo Jin. The group only admits the top one percent of the students in the school. These driven students are all about acing the exams and getting into the most competitive universities. They are under a lot of pressure and it's the kind of pressure that can make nice people do some terrible things.

Some students want to get into the group but don't make the grade.

David Lee, who had a cameo in "Gu Family Book," plays Joon, a bright but not one of the brightest students that longs to get into the elite study group but is cruelly rejected.

Then Yoo Jin is killed and the plot darkens. Joon gets accused of the murder but he is not the only suspect. A detective is called in to investigate. But it's Joon who does the real detective work trying to find the reason for Yoo Jin's death. To clear his own name, he studies Yoo Jin's life. He examines the study group, who gets in and who is excluded.

The title perhaps refers to the fact that Pluto used to be considered a planet and now it has been excluded. It's no longer good enough to rate planet status.

Also in the film is Kim Kkot Bi, who has appeared in dozens of films and won five best actress awards for her work in the 2009 film "Breathless." The film has also cast another "Gu Family Book" alumni. Jo Sung Ha, who played Suzy's father Dam Pyeong Joon in "Gu Family Book," as well as appearing in "Iris 2," will play a role although there is no word yet which character he will play.

The film was shown at the Edinburgh Film Festival in Scotland and will be released next week.