Part 1: Rendezvous With Contact
As soon as you see the first guard tower on the left (it will be very soon after starting the mission) hop out of the truck and climb its ladder. Neutralise the guard at the top. Now go prone and look back in the direction that the truck came from, there will be another two guards entering the base behind it on foot. Stay out of their lines of sight until they reach the base of the guard tower and then eliminate them both. Now activate the search light in the tower.
The light is a signal for the undercover guard to meet you, so climb down the ladder and go prone in the grass nearby. With the ladder at your back, look to the left of the execution ground and wait for a pair of guards to walk down the dirt road here towards your position. Note the video camera on the fence at the bend in the road – don’t enter its view or leave a body there unless you feel like tripping an alarm.
As we wait for the guards approach (sometimes it can take a minute or two), check out your iDroid for a photo of the target. The guard we want to interrogate is the fellow with the bushy head of hair exposed. His comrade can be tranquilised. Once you have interrogated the guard, the location of the tape will be added to your map. It is in the guard tower of the admin building that is overlooking the heliport area.
Part 2: Acquire the Cassette
Enter the execution ground, work your way through the tents to avoid the video camera and then exit onto the road our contact walked down out of its range. Follow the road to the east and when you reach the larger road heading north, work your way along that using the cement blocks and shrubs on the left hand side for cover. Keep an eye out for enemies as you proceed as there are always a couple patrolling around this area. Continue to follow the left hand fence and make your way behind the building via the passage on the left when you are able to do so.
At the end, hop over the barricade and use the shrubs as cover to climb the hill. From the top, look through the fence and use your binoculars to tag any enemies you can see. When it is safe to do so, hop over the fence and work your way along the fence to your left. Neutralise the guard by the orange door and go inside. Walk to the right of the wire fence here and keep an eye out for a ladder along the right hand wall.
Use your binoculars to tag the enemies at ground level here and neutralise any that get too close.
Climb to the top of the aforementioned ladder and follow the catwalk to the end – ensure that you stay crouched as you do or you are likely to be spotted by guards below both inside the admin area and on the helipads outside.
Climb the next ladder at the end of the catwalk up to the guard tower and peek in the doorway. Shoot the video camera on the wall here and then grab the cassette tape from the desk.
itting the video camera here will have put the guards on alert, so quickly exit the guard room, drop down the first ladder and hop over the railing of the catwalk on the right. You should land on a shelf behind a parked truck. If you just want the mission to end and to grab your achievement/trophy right away you can hop into the tray at the back of the truck, go prone and wait for a few minutes for a guard to come and drive you out of the base. However, before you do that, if you are interested, there is an additional, optional cassette tape collectible that can be grabbed at this point as well.
Optional: Find the extra Cassette
If you want to find an additional cassette tape that adds to your collectible tally, we’ll need to backtrack all the way to the start of the mission, find the informant and interrogate him again once the guards have gone back to normal patrol mode. Note that if you took too long getting back he will have moved from where we choked him out and you’ll have to track him down. During the interrogation (it will take a few attempts)he’ll give you the location of another guard in possession of the tape.
Return back to the admin building again and this time, sneak down to the boiler room area, in one of these rooms you will find a bald guard. Sneak up and grab him. Interrogate him until he gives up the tape (this can take several attempts at interrogating, so don’t give up after one!). After he drops the tape, choke him out.
Once you have the tape, return up the stairs, take the first left and hop into the back of the truck. Wait for the guard to drive off and you’ll complete the mission with an extra cassette tape and your achievement/trophy to boot!
Note: Alternatively, instead of tracking down the contact again, you can actually sneak down into the boiler room and grab the bald guy instead of climbing up to the guard tower with the cassette and the camera. If you grab the tape from baldy here, it is entirely possible to complete the mission without ever setting off an alarm. If you have grabbed the guard tower tape, the guards will go into an alert and the guard of interest will leave the boiler rom. During an alert it is possible to locate the bald guard in the field. Just keep an eye out for him on the helipad or sometimes near the guard tower to the east of the execution ground.
Note: For escaping from the mission area whilst hiding on the back of a truck, you will earn the achievement/trophy 'Infiltration'. Collecting the cassette from the admin building's guard tower will reward you with a collectible tape [Agent's Report] , whilst hunting down and interrogating the bald prisoner will yield another cassette [Classified Intel Data] .
Cleared the "Classified Intel Acquisition" Side Op while riding in the back of a truck