Most good stories start with a fundamental list of ingredients: the initial situation, conflict, complication, climax, suspense, denouement, and conclusion. Great writers sometimes shake up the recipe and add some spice.
Exposition (Initial Situation)
College Is Great, Except The Dreams
Dan is breezing through two years of college, getting gymnastics trophies, getting good grades, getting good kisses from Susie—all seems well in the world… except for these nightmares he has about his mortality. We know this is the exposition cuz of that all-seems-well-in-the-world bit: no tension, no complications yet, just a creepy hint (those nightmares) that something ain't right.
Rising Action (Conflict, Complication)
Behold: Socrates!
Dan suddenly meets his eccentric teacher Socrates, and then spends the majority of the book learning his lessons, following his training, getting annoyed by him, etc. This is clearly the rising action since it's all about Dan's struggles to meet Socrates' demands. We watch Dan improve, but from time to time, we still get hints that death scares him, so we wonder if his discipline will overcome that ultimate fear.
Climax (Crisis, Turning Point)
You're Dead, Dude
His training over, Dan drifts away into a mediocre life until he finally decides he's had it with unhappiness and must go into the mountains to find enlightenment—which turns out to be confronting his fear of death, in the final vision Socrates refers to as the gate. We know this is the big climax since the book has been prepping us for an eventual showdown with death—and plus, it's pretty hard to get more ultimate-y than watching a vision of yourself decomposing for thousands of years.
Falling Action
Yay! Unreasonable Happiness!
Dan, successfully through the gate, is now unreasonably happy. He celebrates this with Socrates until Socrates says it is time for him to go—and disappears forever. This is the falling action, because the story arc has been all about Dan and Socrates' teacher-student relationship. The teacher leaving the world brings this arc to its conclusion.
Resolution (Denouement)
End With a Wedding
Dan marries Joy and receives a final message from Socrates—Happiness—and feels his teacher's presence everywhere. It's confirmation that he's completed his training and won happiness.