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.

A young waitress welcomes her husband home to the small South African town of Riviersonderend (Endless River) after his four-year jail sentence. At first it appears their plans for a new life together are finally being realized. But when the family of a foreigner living on a nearby farm is brutally murdered, the young woman and the grieving widower begin gravitating towards each other. Trapped in a cycle of violence and bloodshed, the two form an unlikely bond seeking to transcend their mutual anger, pain and loneliness.