本剧集讲述香港海关特遣队队员在事业上和生活中的点滴故事。在事业上独立果敢的海关特遣队监督吕馥明（汪明荃饰）已投身海关二十多载，年过五十岁的她仍对爱执着，相信至死不渝的爱情存在。出版集团主席涂令山（李修贤饰）感情专一内敛，向不信情。海关督察林志刚（王喜饰）自小受父亲严厉鞭策，性格急进。立志投身海关的特遣队新成员冯满芬（宣萱饰），做事勇往直前，对人生充满理想。在事业上，这些特遣队精英们屡立奇功，而在情感道路上，他们的生活也遭遇了爱的惊涛骇浪。 　　32集香港警务纪实电视剧《雷霆第一关》，由香港TVB知名艺人宣萱、王喜、汪明荃等联袂出演。

Ming Lui devotes all her energy to her job as a customs superintendent. Ming's two capable subordinates, Lam Chi-kong and Moon Fung, always quarrel at work, but at the same time find each other attractive. However, their romance is short-lived, owing to their strong egos, and the two young customs inspectors soon fall in love with Kung Siu-yau and Lam Chi-kit respectively. Ming's newly developed relationship with rich publisher Tao Ling-shan faces challenges from Ling-shan's ex-girlfriend. Meanwhile, at work, Ming, Chi-kong, and Moon are forced to pay increasingly more attention to their careers as law enforcers.