There is an invisible lock in everyone's heart; it hides their unknown secrets, traps them in the reality they are unwilling to face, and isolates them from the outside world.
Married to Yongqi, everything seems happy and perfect for Xiao Yanzi, but secretly there is a storm. Yongqi and Xiaoyanzi are of the same mind as husband and wife. No matter how difficult the road ahead is, they will face it and get through it together...
The secret of the deep palace courtyard begins from this moment... How should Yongqi and Xiaoyanzi deal with these difficulties? Especially when the problem involves Yongqi's long-dead biological mother—Fei Yu! How can Yongqi cheer up and redress her mother's injustice? How can Xiao Yanzi encourage Yongqi, hold hands with him for the rest of his life, maintain their love forever, and be heart-to-heart forever... ——Adapted from Princess Huanzhu's "Heart Lock"