Following the death of his wife and son in a plane crash Choi Kang-woo, former leader of Taeyang Insurance's investigators team, sets up his own team, called 'Mad Dog' that will investigate fraudsters using methods that bend the law somewhat. Two years later he crosses paths with Kim Min-joon, a former fraudster whose brother was the pilot who had according to official reports deliberately crashed the plane. Min-joon believes his brother was innocent and wants Mad Dog to help uncover the truth. Initially they don't trust him but soon they uncover evidence that something is wrong at the airline and insurance company; something certain individuals will go to great lengths to keep secret.
This was a really enjoyable series. There was a good sense of drama, plenty of twists and turns and a real sense of danger at times. There was also plenty of humour which was unforced and didn't get in the way of the story. The 'Mad Dog' team was full of fun and varied characters. The villains are suitably villainous... if airline vice president Joo Hyun-gi had a moustache I'm sure he'd have twirled it! Instead he made do with wearing his tie in a peculiar way. There is lots of scheming as our protagonists work to uncover the truth and the villains seek to hide it or shift the blame onto somebody else. The cast is solid bringing some humour to their roles without getting silly. Overall a solid series that is well worth watching.
These comments are based on watching the series in Korean with English subtitles.