电影《旺角的天空3之终极边缘》讲述了街头少年钱继东（丁子俊 饰）对旺角双鹰成员蒲俊（任达华 饰）的崇拜与追随的故事。钱继东的父亲因欠债被西洋仔（雷宇扬饰）打伤，为了为父亲出气，钱继东决定找西洋仔报仇，却反而被擒获。危急时刻，蒲俊出现并收钱继东为自己的手下，救了他一命。从此，钱继东跟随蒲俊闯荡江湖

然而，钱继东的女友GIGI（黎姿饰）不喜欢他卷入黑社会的生活，劝说无效后最终选择与他分手。西洋仔通过卑鄙手段成为社团的头目，夺取了蒲俊的生意，并导致钱继东的好友子杰被害。蒲俊愤怒之下发现钱继东竟然是警方派来的卧底，他驱逐了钱继东，并决定独自面对西洋仔谈判。然而，蒲俊却被西洋仔抓住。就在此时，钱继东放弃了女友和警察身份，赶到现场，与蒲俊联手对抗，与西洋仔展开了一场激烈的火拼。

《旺角的天空3之终极边缘》通过展示街头少年们的生活、友情与荣誉的考验，揭示了黑社会的残酷和人性的复杂。钱继东追随蒲俊的过程中，经历了忠诚与背叛的交织，以及与女友、警方的冲突。他必须在道义和情感之间做出艰难的选择，最终选择放下身份与蒲俊并肩战斗，共同面对强敌西洋仔。

The movie "The Ultimate Edge of the Sky in Mong Kok 3" tells the story of the street boy Qian Jidong (played by Ding Zijun) and Pu Jun (played by Ren Dahua), a member of the Mong Kok Double Eagles. The story of admiration and following. Qian Jidong's father was injured by Xiyangzai (played by Lei Yuyang) because of debts. In order to vent his anger for his father, Qian Jidong decided to seek revenge from Xiyangzai, but was captured instead. In a critical moment, Pu Jun appeared and took Qian Jidong as his subordinate, saving his life. From then on, Qian Jidong followed Pu Jun through the rivers and lakes

However, Qian Jidong's girlfriend GIGI (Gigi Lai) doesn't like him being involved in the life of the underworld. He breaks up. Xi Yangzi became the leader of the society through despicable means, took Pu Jun's business, and caused Qian Jidong's good friend Zijie to be killed. In anger, Pu Jun discovered that Qian Jidong was actually an undercover agent sent by the police. He expelled Qian Jidong and decided to face Xiyangzi alone for negotiation. However, Pu Jun was caught by Xi Yangzi. At this moment, Qian Jidong gave up his girlfriend and his identity as a policeman, rushed to the scene, joined hands with Pu Jun to fight, and started a fierce fight with Xiyangzi.

"The Ultimate Edge of the Sky in Mongkok 3" reveals the underworld by showing the lives of street teenagers, the test of friendship and honor The cruelty and complexity of humanity. In the process of following Pu Jun, Qian Jidong experienced the intertwining of loyalty and betrayal, as well as conflicts with his girlfriend and the police. He had to make a difficult choice between morality and emotion, and finally chose to let go of his identity and fight side by side with Pu Jun to face the powerful enemy Xiyangzai together.