1979: A fictional police base on the border between Angola and the former South West Africa. While patrolling, a mail convoy is ambushed and most of the soldiers are shot. The captain (Danie Joubert) is rescued, but one of his constables (Tommie Erasmus) is taken prisoner. Die constable’s sister (Karin Kritzinger) is also the captain’s girlfriend. GRENSBASIS 13 (Border Post 13) tells the story of the captain’s suspenseful and action-filled rescue attempt in order to bring his sweetheart’s brother home.