The primary objective of this mission is to identify the Viscount and to extract him to the Mother Base. The game will suggest that you need to follow the Afrikaans interpreter here, but this is not necessary.
The game will suggest here that for this, you need to follow the Afrikaans interpreter, but this is not necessary. You need to follow the interpreter only if you want to unlock the secondary objective connected with eavesdropping on all of the conversations - see the next page for details.
At the beginning of the mission, you can find the Viscount outdoors, to the North-East of Kiziba Camp - the locations has been shown in the above screenshots. He is being guarded by a single soldier, whom you can either stun or kill. After you do this, you only need to fulton the Viscount to the Mother Base, or deliver him to the chopper's landing zone, which will grant you easy S rank for this mission.
Note! The Viscount may not appear on the map during the day. In such a situation, you can use the Phantom Cigar to pass time until nightfall.
If you do not make it quickly to the first location of the Viscount, he will be escorted to the buildings to the North of Kiziba Camp, by the guard. The location has been marked on the screenshots above. This makes things a little bit more complicated, because this will require you to eliminate several more guards, in that area, before you get to the Viscount.
Note - Towards the end of the mission, the Viscount meets the Afrikaans interpreter whom you had the option to follow (the secondary objective of this mission; see the next page). In such a situation, you can eavesdrop on the interrogation. After it ends, try to free the Viscount quickly, or else he may be shot.