The cousin is beautiful but ruthless.

At the tender age of nineteen, Shen Hanyu entered a mansion as a concubine, only to suffer and die. Reborn, she rewrote her destiny. Her two-faced cousin was met with cunning flattery and even more skillful acting from Shen Hanyu than her. Her scheming cousin was lured into a living hell by Shen Hanyu's smiles. Her aunt, fearing she had climbed the social ladder, was eager to marry her off to anyone. Shen Hanyu smiled radiantly; she would rather climb that high branch and trample those who had wronged her underfoot. Everyone said the young master of the Founding Duke's mansion was of unparalleled nobility and abstained from women. Shen Hanyu, using the excuse of being saved, married into the Duke's mansion, becoming his only wife. Everyone felt Pei Du must have had a reason for marrying her, and Shen Hanyu thought so too...