Yai Bai Bah

Beneath the grand mansion of Borirak, a billionaire patriarch, lives a deeply dysfunctional family with four children.
The eldest son, Chaichan, is selfish and uncaring toward his siblings, blindly obeying his greedy wife, Chalalak. The second child, Sudsuang, is a still-beautiful widow who craves love and becomes involved with Samran, a fraudulent businessman who deceives her for money. Even her spoiled daughter, Nokyoong, falls victim to Samran, becoming entangled with him as well.
The third child, Chaimad, is gentle and refined but secretly prefers same-sex relationships. He falls for Sak, a fugitive who only pretends to love him in order to steal money. The youngest daughter, Duangjai, is naïve and soft-hearted. She secretly loves the family doctor, Prawit, but he instead has feelings for Sabai—a beautiful yet mentally unstable girl whom Borirak took in out of pity.
Borirak treats Sabai like his own daughter, which sparks jealousy among his children. Chaos erupts during Borirak’s birthday party when Sudsuang and Nokyoong lock Sabai in a storage room, causing her to be trapped in a fire. Fortunately, Kawin and lawyer Sompoch arrive in time to rescue her.
Later, out of jealousy, Duangjai pushes Sabai into the sea, but Kawin once again saves her. Before Borirak dies, he gives Sabai a locket as a keepsake. His death devastates Sabai so much that she faints. When she regains consciousness, her mental illness is mysteriously cured—but she continues to pretend to be insane. Only Dr. Prawit knows the truth. Sabai keeps up the act because she fears Borirak’s children will harm her, especially after learning that his will states all his assets will go to whoever takes care of her.
As a result, each family member competes to care for Sabai, hoping to inherit the fortune. However, instead of kindness, they constantly plot to get rid of her. Sabai cleverly retaliates each time, making them increasingly wary of her.
Eventually, lawyer Sompoch assigns Kawin to take full responsibility for Sabai—teaching her, guiding her, and helping her adjust to life. As they grow closer, Kawin begins to suspect that Sabai is far more intelligent than she pretends. Meanwhile, Nokyoong, who secretly likes Kawin, grows jealous and causes trouble for Sabai.
When no one can truly manage Sabai, Sompoch refuses to reveal the will. Chaimad and Sak, manipulated by Chaichan and Chalalak, murder the lawyer to obtain it. But when they finally open the will, they discover that Borirak has donated all his wealth to charity.
Desperate, the family searches for the key to the mansion’s safe, believing there is still hidden treasure. Nokyoong overhears Kawin and Sabai discussing it and tells Sudsuang that Sabai knows where the key is. Sudsuang and Chaimad then kidnap and torture Sabai to force her to reveal its location.
In pain and delirium, Sabai unintentionally reveals the hiding place. Chaichan and Chalalak, who have been secretly listening, rush back to the mansion to find the key.
Now, the question remains: who will ultimately claim the vast fortune in the safe? Will Sabai survive her ordeal? And what will Kawin do when he realizes he has fallen in love with a woman everyone believes to be insane?