A crocodile never lets go until its prey is dead.
At the age of 19, Jung In-hoo committed murder and subsequently served a 10-year prison sentence.

Upon his release, he dreams of starting a new life, but reality proves to be far from easy.

Then one day, Yoon Jin-hee, the wife of Kim Sang-chul—the man he killed in the past—comes to him with an unexpected offer: to act as a personal bodyguard for her son, Kim Roo-hwan.