Tong Mansion and Ye Mansion are the two largest families in Luoyang City, and the relationship between the two houses is extremely close. Eighteen years ago, Mrs. Tong and Mrs. Ye were both pregnant. Mr. Tong promised that as long as Mrs. Tong gave birth to a legitimate son, he would give his son a key. It was said that this key was extremely important, and whoever got the key would win the world. Then eighteen years later, the key actually hung on a Ordinary woman - Tang Zixuan's neck. Her parents left one after another for this key. Without finding out the truth, to avenge her parents, Zixuan entered the Ye Mansion. The journey was full of dangers. She followed the Ye Mansion's daughter to the Tong Mansion again, and had a secret love affair with the second young master of the Tong Mansion. Undercurrents surged in the house. What is the mystery of the key? What is the truth behind the truth? Who should she believe?