Private investigator AU YEUNG YAT gets acquainted with a woman in a casino. He is later alleged of murder when the woman falls down her house and dies. After investigation, YAT discovers that it is all his father SUN's plot. SUN hopes that YAT will succeed his business, but YAT refuses. Business brothers TUNG YAT-FUNG and YI-FUNG arrive in Shanghai. SUN is emotionally stirred when he sees YAT-FUNG. SUN's man CHAN HUNG kills Gang leader TIN PUI's subordinate. SUN promises to handle TIN PUI for CHAN.

TIN PUI refuses to talk peace with SUN. In a fight, he has CHAN HUNG killed. YAT-FUNG discovers that SUN is his father. But he is prevented from reuniting with SUN by MA KWUN. For fear that YAT-FUNG will be reunited with SUN, MA KWUN sends a killer to get SUN. SUN dies, but his subordinate SHAN survives. YAT is shocked to learn of SUN's death. Everybody suspects TIN PUI to be the murderer. SHAN is attacked by a killer. He is saved by NAM, SUN's helper.