Ki-joon and Hee-yeol are students at the Korean National Police University.
At around midnight one night, they witness a kidnapping on their way back from the club. The local police station's missing persons department, however, is busy with the kidnapping of a son of a business mogul at the time and is unable to investigate the case. Knowing that they are in the critical hours after a kidnapping, they embark on their own amateur investigation.
When Ki-joon and Hee-yeol catch up with the kidnappers, it appears that the gang is running an unfertilized egg harvesting ring and there are many more girls locked up at their hideout. Ki-joon and Hee-yeol tries to save them but are instead beaten and locked up.
After escaping their captors, they return the next day to an empty hideout and a cold trail. As they are not acting police officers, their professor tells them not to pursue the case any further. Unable to wait for the bureaucracy to resolve the case, they once again embark on their own investigation. They undergo heavy physical training and manage to track the kidnappers down, with the help of CCTV footage, to a fertility clinic. Armored up, the duo venture in to liberate the girls by themselves, this time much more prepared. They successfully take down all the kidnappers and their boss. Unable to arrest the kidnappers and rescue all the kidnapped girls themselves, they call the police in, knowing they might get expelled for their actions. However, due to some among the disciplinary committee believing that they had done the right thing morally, they are instead held back a year in their studies and sentenced to 500 hours of community service, leaving the two satisfied with the outcome.
In a mid-credit scene, the girl kidnapped at the beginning of the film visits Ki-joon and Hee-yeol as they're serving their community service and thanks them for rescuing her.
