I can't write a description so just read the tags

Irene is hired as a teenage spy and sent to a girls and boys boarding school to track down the teenage boy said to have witnessed the murder of Kim Dongwook. A popular actor. She has nine suspects in mind, and knows one of them could be the killer. If she can get a confession, that's one million dollars in the bank and  freedom in her future. But with these nine boys always together and not so easy to get, how will she ever get the truth?