CS, the acronym for an international financial fraud organization.
This organization mainly operated in Europe, using financing schemes to defraud funds. They were skilled and left no trace. Five years ago, the bankruptcy of a top 500 global corporation led to a worldwide financial crisis, which was their doing.
Later, they were wanted by police from several countries, and their members scattered and hid deeply. With powerful forces behind them, they had been quiet for years, but surprisingly appeared domestically.
Zhou Ling was one of their members.