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 Watch drama online for free.