Anonymous Signal.

Former friends Kwok Pak-fei, Keung Hei-man, and Lau Lik reunite years after a botched operation led to a tragic death and estrangement. Now, a gruesome murder case tied to a human trafficking ring forces them to work together. As they investigate, mysterious messages appear with clues about the crimes, hinting at knowledge from the future. Together, they form a special unit, ASIB, to decode these messages and solve the chilling case.