Widow Tong Suk-fan is saddled with hardship alone, struggling to bring up her two sons Chong Yau-ching and Chong Yau-kit. The brothers join the Intelligence Unit and the Operations Unit of Anti-Terrorist Force respectively, and both gain recognition from their superior Shum Chi-ngo, which is supposed to be a comfort to their mother. But unexpectedly, due to a mysterious piece of intelligence, their brotherhood turns to enmity..