This series was adapted from a novel of the same title, written by the renowned wuxia novelist Wen Rui-An. "Strike at Heart" tells the tale of friendship, loyalty, love and revenge about Marquis Chu Kot and his friends in their younger days. Marquis Chu Kot was the master of The Four Constables - there were plenty of series adaptations on the four constables by ATV, Taiwan and Mainland China. Therefore, "Strike At Heart" can be considered a prequel. TYGS (Sunny Chan), Chu Kot (Joe Ma) and Thirteen (Stephen Au) studied under the same martial arts clique Zhi Joi Mun since childhood. Tje three of them forged a strong bond and each had a special skill of their own. TYGS was intelligent but physically weak, therefore he turned to studying yin yang and the five material agents. Chu Kot and Thirteen were talented in martial arts and learnt "Amazing Spear" and "Heartbroken Arrow" respectively from their master. After being separated for more than 10 years, the brothers finally reunited but ended up at daggers drawn. After leaving the clique Chu Kot served the imperial government and was one of the emperor's favorite officials. His mission was to protect the country from the Gum invasion and corrupt minister Choi Ging (Shek Sau) and his assistant Zhong Shu (Derek Kwok). Thirteen resented the fact that he was unable to beat Chu Kot before leaving the clique and spent 10 years practicing martial arts in the hope of defeating him one day. TYGS enjoyed a carefree life at Bak Soh Yuen, immersing himself in chess, qin, and his pet tortoise Gum Chai. Thirteen returned and demanded a duel with Chu Kot. Chu Kot was unwilling to fight him, but had no choice due to Choi Ging's constant meddling and manipulating the na? Thirteen. Their conflicts were aggravated when both of them fell in love with the gentle and cheerful Siu Keng (Charmaine Sheh). Meanwhile, the impulsive Jik Nui (Annie Man) from Divine Needle Sect met TYGS after a misunderstanding. She fell for his gentlemanly ways and forced TYGS to marry her. To salvage their friendship, Chu Kot decided to back away from the love triangle and pushed Siu Keng away with the help of Mong Dip (Nnadia Chan), a famous singer-prostitute. On the night of her wedding to Thirteen, Siu Keng found out the truth and hated Chu Kot for giving her away like a toy. She vowed revenge and wanted to destroy everything he stood for ? his friendship, loyalty and honor. TYGS was accustomed to living alone and constantly neglected Jik Nui because he regarded her as a nuisance. Jik Nui tried to change her behavior to please TYGS, but he preferred to pay attention to his pet tortoise Gum Chai. Under Siu Keng's manipulation, Thirteen began to go against Chu Kot and went berserk after attempting to master an internal martial arts manual "San Tze Ging". Chu Kot was also learning the same manual as he wanted to cure Mong Dip of poison. Mong Dip was actually sent to spy on Chu Kot by her lover and master Choi Ging. Mong Dip was saddened and disappointed when she realized Choi Ging killed her baby and tried to commit suicide with him. She failed and died in Chu Kot's arms. Siu Keng was saddened to hear of Chu Kot's death and regretted her actions. She went to his grave to confess that she still loved him. Thirteen overheard this and was hurt that Siu Keng married him for revenge. He went berserk again and injured himself. Feeling guilty, Siu Keng went to look for a cure from the Taoist priest Sam Bin and was saved by Chu Kot from his lecherous hands. Siu Keng begged Chu Kot to elope with her but he refused because he had too many responsibilities. Knowing that Chu Kot faked death, Choi Ging set up a trap and accused him of betraying the country with the Gum people. TYGS and Jik Nui became fugitives trying to help Chu Kot. On the other hand, Siu Keng decided to stick with Thirteen but he was narrow-minded and constantly accused her of having affair with Chu Kot. Desperate to please Thirteen, Siu Keng agreed to retrieve the full copy of San Tze Ging from Sam Bin ? only to be raped in exchange for the top half of the manual. Chu Kot found out about this and killed the Taoist priest when Siu Keng returned to get the remaining manual. Ashamed, she tried to commit suicide. Thirteen flew into a rage thinking Chu Kot was after his wife and tried to kill him. Siu Keng ran out and broke his arrow to save Chu Kot. Embittered, Thirteen finally understood the true meaning of "Heartbroken Arrow". Chu Kot narrowly escaped with the wounded Siu Keng. Jik Nui went through thick and thin with TYGS and he realized he had fallen for her. However, TYGS had to divorce her because he didn?t want her to get involved with Chu Kot's problem. Humiliated and filled with hatred, Thirteen vowed to kill Chu Kot and anyone who dared to stand in his way. Choi Ging seized this opportunity to manipulate Thirteen to assist him in abducting the emperor. Jik Nui attempted to lure Thirteen and assassinate him with the help of Divine Needle Sect but she was defeated and thrown down the cliff. TYGS arrived too late and regretted not appreciating Jik Nui when he had the chance. After he fully mastered the San Tze Ging, Thirteen was invincible. Chu Kot studied the secret of "Amazing Spear" in order to defeat Thirteen's "Heartbroken Arrow". Touched by Siu Keng's undying devotion, Chu Kot promised to live in seclusion with her after he settled his problems with Choi Ging and Thirteen. Siu Keng was overjoyed that they could finally be together? Even though he knew he couldn't defeat Thirteen, Chu Kot had no choice but to walk into Choi Ging's trap as he wanted to save the emperor. Thirteen couldn't bring himself to kill Siu Keng when she begged him not to hurt Chu Kot as he still loved her. Siu Keng killed herself with the arrow after telling Thirteen she was raped in order to get him the manual - Thirteen was remorseful but it was already too late. Siu Keng died peacefully in Chu Kot's arms knowing that Thirteen had forgiven them. Chu Kot and Thirteen were extremely grieved. Choi Ging's martial arts were destroyed because he was injured by Thirteen arrow, rendering him useless. The emperor exiled him to foreign lands to make him suffer for his past wrongdoings. Since they both had no more burdens, Thirteen and Chu Kot had their final duel in front of Siu Keng's altar (how ironic - she died to stop them from fighting, and what are they doing now?). Chu Kot achieved a breakthrough with his "Amazing Spear" final skill and beat Thirteen. Unable to live with defeat, Thirteen committed suicide. Jik Nui survived her fall and was reunited with TYGS. They became a loving couple and soon Jik Nui was pregnant. Chu Kot continued to serve the emperor, but felt empty without Siu Keng.