From the introduction:
Future/Perfect is a series of investigations linked together to form a single unbroken campaign. However, each investigation is self-contained and can be run as a one-off adventure.
The campaign is a great way to introduce new players to the world of Delta Green. They can be brought in completely ignorant of the conspiracy, or with some foreknowledge.
In any case, I hope you enjoy it.
Originally proposed as a 10-part series of linked scenarios, later revised down to four parts. Part 4 is available separately.