Like many of Jin Yong's novels, such as "Legend of the Condor Heroes", HSDS does not start with the main characters themselves, but their parents. Zhang Cuishan (Alec Su) is a respected and righteous Wu Dang disciple. His sifu is the remarkable Zhang Sanfeng. In an encounter, he saves the life of Yin Susu (Phyllis Quek a.k.a Guo Feili), the daughter of the Heaven Eagle Sect, which Wu Dang is against. Yin Susu is trying to steal the Tu Long Dao from Cuishan's fellow disciple. In Cuishan's attempt to find Susu, they are both kidnapped by Xie Xun (Xu Jinhong), a notorious member of the Ming Sect. When the waves grow rough, the three of them end up on Bing Huo Dao (Ice and Fire Island). Although Cuishan and Susu feel angst towards each other initially, they both later soften up and begin to fall in love. Realizing they are the only two on the island besides Xie Xun, the two get married and have a child. When their child is born, Xie Xun is suddenly compassionate and names the child Zhang Wuji, based on the name he gave his own child, who died at the hands of Cheng Kun (Zhang Guoli).
A decade or so passes with all of them living in Bing Huo Dao. Wuji learns martial arts from Xie Xun, his godfather. One day, the tides finally change. Cuishan, Susu, and their son Wuji sail for mainland, while Xie Xun remains on the island. Once they arrive, they are all interrogated by people looking for the whereabouts of Xie Xun. Because of this, Cuishan and Susu are both forced to commit suicide. Before she dies, Susu tells Wuji never to trust beautiful women. Meanwhile, Wuji is left with a fatal sickness caused by Cheng Kun.
After Cuishan and Susu's death, Zhang Sanfeng decides to let Wuji go to visit Doctor Hu, who is a brilliant doctor but does not treat patients who are not part of the Ming Sect. Wuji manages to impress Doctor Hu with his intelligence, however. After some arguments, the two actually develop a strong relationship, and Wuji's health improves. Unfortunately, Doctor Hu and his wife are later forced to flee. Although Wuji thought there was no more hope for his life, but manages to find the 9 Yang manual. After learning the entire manual, Wuji is healthy again and his martial arts ability is extremely high.
The adult Wuji (Alec Su again), through a series of events, manages to become the leader of the Ming Sect. He has romances with four girls - Zhao Min (Alyssa Chia), a Mongolian princess; Zhou Zhiruo (Gao Yuanyuan), the daughter of a fisherman Wuji met at birth, as well as a member of the Emei Sect; Zhu Er/Yin Li (Chen Shasha), a moody but compassionate girl who is actually his cousin; and finally Xiao Zhao (Florence Tan a.k.a Chen Xiuli), a girl from Persia who takes care of him. Initially, he likes Zhou Zhiruo, but he later feels a deeper attraction to Zhao Min. Meanwhile, everyone's search for the Yi Tian Jian and Tu Long Dao causes an unexpected twist and turn of events...