Beijing detective Li Yan, now based at the Chinese embassy in Washington, is dispatched to find out how his fellow countrymen suffocated in a sealed refrigeration unit in southern Texas - only to find himself face to face with the woman who walked out of China, and his life, to return to the U.S. Tasked to work together again to find out who is behind the 100-million-dollar trade in illegal Chinese immigrants which led to the tragedy in Texas, they discover that the immigrants were unwitting carriers of a deadly cargo. Still wrestling with the demons of their past, Li and Margaret find themselves racing against time to defuse a biological time-bomb that threatens to wipe out not only their future, but that of humankind.