All of the Story Design guides help me find the key story beats for my adventure, broken down into act I, act II, and act III. I find preparing with some points in mind doesn't limit player agency and heightens the tension and reward.

I bought all these in a bundle and they're quick and handy references. The price is right either way.

Chase could have been a little more concise (14 pages could have been 7), but the reminders are useful for setting up a subplot and resources that change the direction in the second act.