Yoon Hyun-woo (Song Joong Ki) is a dedicated and loyal employee of Soonyang Group. However, the company frames him for embezzlement and gets him shot in the head. He wakes up in the past as Jin Do Jun, the youngest grandson of the Soonyang patriarch, Chairman Jin Yang Cheol (Lee Sung-min). Yet he retains the memory of his previous 30+ year-old self. Armed with knowledge of what would happen in the future, he enacts his revenge against the family that destroyed his own in his old life. He also befriends a young law student Seo Min-young (Shin Hyun-been) who he knows would become an anti-corruption biggie and Soonyang family's "grim reaper" in the future.
Imagine knowing events before they happen such as which presidential candidate would win or which stocks would bubble and burst. It's every financial investor's dream. No wonder this became a huge hit in Korea.
Up to episode 15, the drama seems like any other about members of a ruling family fighting for the top position in the company, albeit one of them has knowledge about the future in his disposal. But the way episode 16 wraps it up in the end pulls it far ahead from the pack. Some viewers have expressed disappointment over the ending but I love it. It's mind-boggling and, for me, confirms Korean drama writers' brilliance.