There are 59 Missions in the game, which are split up into 5 Chapters, but the Missions you encounter within them can change depending on what you do when you have to make a Decision. Your choices lead to one of three different endings, but you'll always have to work through the same number of Chapters. Broken down into multiple Missions, you can find more information on each via the links below:
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
New Game+
New Game++
If you want to find a different path through the Chapters, then the New Game+ option will be perfect for you. Refer to our How to Start New Game+ and What Carries Over guide for more guidance.