Plerngrit, or simply Plerng (played by Mario Maurer), is the only son of Pipat and Pongpaew, who lives in Ranong and does fishing for a living. Pipat is actually the eldest son of Khun Ying Tongtraa Chatayothin, the owner of Thai Diamonds Company, or Phet Thai. Twenty years back, Pipat fell in love with Pongpaew, a poor woman who Khun Ying Tongtraa despised. Pipat was given two choices: stay with his mother or leave the house and go with Pongpaew. He chose option number two and lived a peaceful life in Ranong with his family.

For twenty years, Plerng’s parents hid the truth from him. However, one day, Khun Ying Tongtraa fell ill and ended up in the hospital requiring immediate heart transplant. The news spreaded throughout Thailand and reaches Pipat. Pipat finally decides to tell his son the truth and the family travels to Bangkok to visit Khun Ying Tongtraa in the hospital and apologize for his actions twenty years before. On the way, they get into a wreck and Plerng’s father dies on the scene. Plerng and his mother, Pongpaew ended up in the same hospital as Khun Ying Tongtraa. When Plerng was conscious, he learned that his father had passed away and his grandmother was at the same hospital. The doctor tells Plerng that his father is brain dead and will never wake up.Plerng didn’t want to see his father in that horrible situation so he decides to let his father go and donate his father’s heart to his grandmother. He made the decision alone because his mother was still in a coma.

While at the hospital, Plerng meets his aunt Bussakon and uncle Niruj. His aunt Bussakon has two children: Anat and Naree. His uncle Niruj has a son named Chanon. Uncle Niruj and Chanon accepts the truth that Plerng is their relative but aunt Bussakon and her children do not like Plerng. They are jealous of Plerng and fear that one day, Plerng will come into the family and take over everything. For that reason, aunt Bussakon tricks Plerng and Niruj to hide the truth from Khun Ying Tongtraa about the heart transplant.

When Plerng’s mother is finally conscious, she learns that her husband has passed away. Plerng also tells his mother about the heart transplant but his mother does not blame him. Since Plerng promised to hide the truth about his father’s heart, Plerng and his mother decides to leave the hospital without seeing Khun Ying Tongtraa.

However, fate leads them to meet and before he knows it, Plerng finds himself living and working with his family under stressful conditions. When Khun Ying Tongtraa learns that her son is dead, she is very sad and blames Pongpaew for taking her son away forever. Plerng and his mother want to apologize to his grandmother but his grandmother would not listen. She refuses to forgive Pipat and Pongpaew. But, Plerng does not give up. Khun Ying Tongtraa uses his chance to allow Plerng to prove himself. Plerng’s father has 20% of the shares in Phet Thai. Unless Plerng can make the profits higher than his father’s shares within three months, his grandmother will not accept the apologies.

So Plerng takes over his father’s position and bring up the sales in Phet Thai. With the help of the two sisters, Namfon and Sitha, and their mother, Khun Manmart; Plerng is only a few steps away from achieving his goal. As they spend a lot of time working with each other, Plerng gradually falls for Namfon while Namfon’s older sister, Sitha falls for Plerng. Chanon, on the other hand has a crush on Sitha. When he learns that Sitha loves Plerng, he respects her decision and tries to hold his feelings back. Will Chanon end up with Sitha? How will Khun Ying Tongtraa react when she learns that her heart donor is her own son? Tune in to Plerng Torranong to find out!