***Spoiler if you didn't play the campaign***
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@Yubikiri
If you mean why did Mason "escape," it is because he finally remembered then number station -- in which was located on a big boat. He went on a mission with Hudson and a lot of other people to take down the ship and murder Dragovich by drowning him in water. Hudson and Weaver got everything that Mason knew. They just wanted the numbers, the number station that was broadcasting to multiple places. Why did they want it? They want it because Dragovich and a lot of other people are performing a world-changing event that will kill most of everyone on Earth by this sort of Nova gas or something related. The government is then on DEFCON 2 and is launching nuclear missiles. Mason is the world's last hope. That is why they got him in the pentagon in an interrogation facility. So at the end, Dragovich was murdered and Mason went on future secret C.I.A missions. Now, Mason was still brainwashed. He was never... actually fixed. That is why they all were suspicious of Mason, in which Hudson and other people were always on Mason's behalf when doing missions in case he does something wrong due to the brainwash that screwed him up.