『線路檢(jian)測永久(jiu)』介(jie)紹:碧(bi)生(sheng)與碧(bi)琪為朝街私鐘妹,感情甚篤,合稱朝街雙Big。因生(sheng)欠下賭款,琪請其男友龍(long)(long)代(dai)出(chu)(chu)頭,與西洋(yang)(yang)(yang)仔(zi)結怨,后琪被(bei)(bei)西洋(yang)(yang)(yang)仔(zi)擄走,生(sheng)、龍(long)(long)為尋回(hui)琪,出(chu)(chu)生(sheng)入死,漸生(sheng)情愫,琪被(bei)(bei)救回(hui)后,發現生(sheng)、龍(long)(long)關(guan)系(xi),與生(sheng)漸疏遠。另方(fang)面,生(sheng)結識老差骨麥(mai)(mai)Sir,成為好友,麥(mai)(mai)Sir更對生(sheng)存(cun)有父(fu)女間的情義(yi)。麥(mai)(mai)Sir數度追捕龍(long)(long),均被(bei)(bei)上司靚Sir阻止,卻(que)原來龍(long)(long)乃臥底,直屬于(yu)靚Sir,后靚Sir被(bei)(bei)西洋(yang)(yang)(yang)仔(zi)所殺,龍(long)(long)被(bei)(bei)麥(mai)(mai)Sir苦(ku)苦(ku)追緝,無從證實(shi)自己身份。西洋(yang)(yang)(yang)仔(zi)因私竇被(bei)(bei)搗,擄走麥(mai)(mai)Sir兒(er)子(zi)小杰(jie),逼麥(mai)(mai)Sir替其殺死龍(long)(long),危急中,困于(yu)麻袋中的生(sheng)脫(tuo)縛撲(pu)出(chu)(chu),一(yi)個血人撲(pu)向西洋(yang)(yang)(yang)仔(zi)……