Watch Grensbasis 13 for Free: How to Stream the Movie Online at 123Movies. . A story about a fictional South African 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 is rescued, but one of his constables is taken prisoner. The constable’s sister 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.