Four of China's supremely skilled assassin/detectives serve only their Master Zhuge Zhen-Wo - The Little Flower, who in turn is head bodyguard and advisor for China's all powerful Emperor. Yet the Constables' reputation strongly precedes them:

The Emotionless cripple is a master of weapons and devices.
The Iron Hand possesses incredible chi and can stop the sharpest blades bare-handed.
The Life Snatcher is highly skilled in lightfoot granting him undaunted legwork.
The Cold Blooded was raised by wolves and since learned to transfer his pain when fighting to strength enabling him to defeat opponents much stronger than himself.

Each of them is entrusted by the Emperor with the power to arrest and execute any corrupt officials or lawless criminals with the Chinese Empire. These Imperial Constables act as protectors. With their venerable skill they root out potential usurpers and discern the cause of many strange occurrences happening during Sung Dynasty!