The Three Old Boys detective team helped the security team investigate underground gambling cases. Cui Tiejun disguised himself as a gambler and sneaked into the casino.But they found that the casino was very small and it was impossible to obtain 20 million in illegal income in a short period of time.Cui Tiejun heard from Wei Meng, the casino owner, that there was a bigger gambling game. Cui Tiejun decided to take a long-term approach to fishing for big fish and find a way to find out the bigger gambling gang behind it.However, Cui Tiejun's plan was opposed by Chu Dongyang. After weighing the situation, Lin Nan decided to adopt Cui Tiejun's suggestion and sent Xu Guozhu and Xiao Lu to form a team to monitor Wei Meng, but Wei Meng accidentally got rid of his tracking.