The unit specializes in the investigation of serial murders and is led by Van der Bijl, a former murder and robbery detective who gained fame for his handling of several high-profile cases. Each episode focuses on a serial killer. The main character, Colonel Piet van der Bijl, also known as Die Byl, is loosely modeled on the famous ex-detective Piet Byleveld.

When two young lovers are savagely beaten and tortured on a back country road in Texarkana, local police are baffled and must find "the Phantom Killer" before he can kill again.