'Four Sons' centers around the story of a man who is trying to uncover the truth behind his mother's suspicious death when he begins to meet individuals who have the same face as him. The series stars Park Hae Jin as the male lead alongside Nana, Kwak Si Yang, Lee Ki Woo, Kim Chang Wan, and more, and is a fantasy romance crime drama. It is also the return project of director Jang Tae Gyu, 4 years after his hit series 'You Who Came From The Stars'. The cast is currently busy in active filming. 

As you can see in the behind-the-scenes cuts below, all of the cast and staff seem to be getting along very well while hard at work! Park Hae Jin and Kwak Si Yang may be building up a strong bromance, while Park Hae Jin and Nana seem to be getting close in order to create more natural scenes together. Meanwhile, 'Four Sons' is slated to premiere sometime later this year.