In a world where crossing the river between two rival kingdoms is forbidden, Prince Jeonghan defies the law out of curiosity, accompanied by his loyal friend Joshua. Disguised as a servant in the opposing kingdom's castle, Jeonghan finds himself as the personal assistant to Prince Seungcheol. What begins as a dangerous game of secrets soon blossoms into a forbidden love between the two princes. But when Jeonghans escape is found out, they face the dangers that awaits them. How far will Jeonghan and Seungcheol go for their love?