"Khem Sorn Plai" is the story of a beautiful girl named Cherd, who is stuck in a marriage with Dr. Ruengboon in an overseas country. In a loveless marriage, she finds herself falling for, Lanna, a Thai student who has come overseas to study. However, Dr. Ruengboon refuses to give Cherd a divorce and this keeps her bound to him unwillingly.
Eventually, Lanna returns to Thailand and begins a new life by marrying Yaowayod, a young woman who is perfect in both looks and social status — and most of all was chosen for him by his mother. Despite having a sweet wife, Lanna can not forget Cherd and continues to keep the dazzling girl in his heart silently.
When Dr. Ruengboon discovers that Lanna has gotten married, he finally divorces Cherd and so she too returns to Thailand and begins a new life. However, despite many young men ready to peruse her, she still holds a lit candle for Lanna — unable to forget him. And what of Lanna, who expresses the desire to get together with Cherd again, while not wanting to break up with his wife Yaowayod?
The hidden needle in this story is the expression of passions in young men and women and how Cherd, after a long period of being misguided, decides to be free of the debt of the word "love".