香港六七十年代，警黑勾结，贪污横行，社会怨气极重。这时候，生性善良率直的徐乐（王浩信 饰），由于家境不好，辍学加入警界，穿上警服，成为最普通的警员。初出茅庐却因为破获一场抢劫案得罪龙探长（李子雄 饰）舅甥，而遭到排挤贬压，调职到下水警局。处理事故纠纷时，帮助并结识了富家千金白珍妮（徐冬冬 饰），白珍妮对徐乐一见钟情。一方是一直陪伴自己的女朋友阿贞（云千千 饰），一方是能让自己摆脱困境的富家千金小姐，面临着权利与爱情的选择。徐乐如何扭转乾坤，步步高升，成为一代传奇探长......
The film opens in a bleak police station where celebrated war correspondent Kate Rafter (Seagrove) faces questions from a psychiatrist, Dr Shaw (Kurylenko), as they work through the painful events of Rafter’s life. A horrific incident in war-torn Iraq and the death of her mother (Steed) have brought a haunted Rafter home to Herne Bay, a place she believed she had escaped forever. Her resentful sister (Friel) has not made her sister welcome and her forbearing husband Paul (Miles) fails to broker peace. Whilst packing up her mother’s belongings from her childhood home, Rafter comes to believe there is something strange and terrifying happening in the house next door.
