Special Affairs Team TEN is a criminal investigation unit that tackles the most violent crimes in South Korea. These crimes usually have less than a 10% rate for arrests. They chase the most notorious killers who attempt to commit the perfect crimes.
Yeo Ji-Hoon (Joo Sang-Wook) is former top-notch detective, but now works as a professor. He then becomes the leader of Special Affairs Team TEN. Nam Ye-Ri (Jo An) has been a detective for 4 years. She joins Special Affairs Team TEN because of her psychological reasoning powers. Baek Do-Sik (Kim Sang-Ho) is 24 year veteran detective. He possesses a keen sense of intuition, which he honed from his many years as a detective. Bae Do-Sik also joins Special Affairs Team TEN. Park Min-Ho (Choi Woo-Sik) is a new detective. He joins Special Affairs Team TEN after impressing Professor Yeo Ji-Hoon with his reasoning powers.
This is the story of two women, Seo Jung Eun and Han Yoo Kyung, who walk very different paths to achieve their desires. Seo Jung Eun is a strong and courageous woman who has suffered a difficult life, having grown up in an orphanage, but continues to embrace people around her despite longing for affection herself. Jung Eun harbours the hope that she will meet her mother if she becomes a star, striving to reach her goal and overcome her suffering with her pure and innocent nature. In contrast, Han Yoo Kyung has a birth secret for which she is willing to throw away everything in order to get revenge. The "thorn birds" of the title refers to Jung Eun's character, who only brings out her best at the cost of great pain. A thorn bird is a mythical bird who searches for a thorn tree from the day it is born. When it finds it, the bird impales itself upon the sharpest thorn, and rises above the agony to sing the most beautiful song ever heard.
Dong Joo and Da Ji were once a couple who were married at 19 but they quickly divorced. Years passed, they both return to their old house and discover that their feelings for each other have been endured.
It all started with football. Deok-hoon falls in love with In-ah who shares his love and passion for the sports. They quickly become lovers and he proposes. She refuses at first but they are eventually happily married. Marriage is like a dream until one day In-ah declares her wish to marry another man. She doesn’t want divorce as she loves Deok-hoon all the same, only change is that she loves the new man as much. Leaving Deok-hoon who finds himself unable to leave In-ah in the middle, she goes ahead and marries her new man. And so the bizarre bigamy begins.
Song Na Young and her husband, Jung Sung Min, desperately want a child but her husband is unable to get her pregnant. Her husband's friends decide to help them. But Na Young suddenly loses her husband in an accident and she gives birth to her daughter but does not know which of her husband's friends fathered her child. The father of Na Young's child can either be Han Soo Hyun, Choi Kwang Hee, or Hwang Kyung Tae.
Even though times change and our relationships with our family changes, our affection for them is timeless. The drama is about affection that is the foundation of family. Dong Jin is the eldest son in a family of 3 sons. He is dutiful and responsible but due to character clash, he has gone through divorce with his ex-wife, Ji Hye, whom he shares a child with. Dong Jin then starts a new romance with Eun Ho whom he works with.