Bossam was a custom in Joseon period, in which a bachelor, who missed marriage secretly wrapped up a widow in a blanket at night and made her his wife.
This custom changes the fate of Ba Woo (Jung Il Woo) and Soo Kyung (Kwon Yoo Ri), when Ba Woo kidnaps by mistake princess Soo Kyung, who was daughter of Gwanghae-gun and a blue widow.