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.
Initial Situation
John wonders who his father is. Tabby marries Dan.
As John starts to set the scene for us, we learn about some pretty key circumstances that help put the story in motion. As we are introduced to our main characters, we learn that John is on a lifelong quest to figure out who his father is. He gets a wonderful surrogate dad, though, when Tabby marries Dan. Everything seems to be in perfect order.
Conflict
Owen kills Tabby when he hits a foul ball that then hits her in the head.
John's quest to figure out his dad's identity is put on hold when Owen accidentally kills Tabby. Not only does John lose his mother, whom he loves dearly, but now his father's identity is even more of a mystery. Tabby's death also has major implications for Owen: he becomes convinced that it's a sign from God that he is God's Instrument. The event of Tabby's death also presents John and Owen with a difficult challenge – how can a friendship go back to normal when you've killed your best friend's mom?
Complication
Owen becomes convinced that he's God's Instrument; he strives to figure out what his purpose is. Meanwhile, he sees the date of his death on the tombstone during the production of A Christmas Carol.
OK, as if Owen didn't already think that God was meddling in his life in interesting ways when Tabby dies, now he is convinced that he knows exactly when he's going to die. Owen's belief that God has a specific plan for him is solidified by what he takes to be signs from the beyond. While we don't find out until the end what the exact date is, Owen starts operating like he's only got a limited time to live. He starts thinking seriously about what role he wants to have in the world and what impact he would like his actions to make. Think about it: wouldn't you be careful about how you spent your time if you thought you didn't have a whole lot of it left?
Climax
Owen dies saving a bunch of children from a grenade.
Even though it happens at the end of the novel, Owen's death is the most central, explosive event in the story (literally…thank you, folks, we'll be here all night!). It is the moment that all of Owen's actions have been building up to throughout his entire adolescence and young adulthood. It's also a major game-changing moment for John. John never really believed Owen's claims about fate or belief when Owen was alive. All of a sudden, Owen dies, and, as far as John is concerned, it's some kind of divine proof that guides his beliefs and actions for the rest of his life.
Suspense
John has two weird "encounters" with Owen. During one of them, he finds out who his father is.
John has a couple of spooky experiences in which Owen seems to visit from beyond the grave. The first happens right before Owen's funeral: Owen somehow speaks through Rev. Merrill and tells John where he can find the baseball that killed Tabby (this is the kind of magic that doesn't just belong to television, people). Just like that, we find out that Rev. Merrill is actually John's father (Owen was right – what a letdown!). Years later, Dan and John are at 80 Front Street, drinking some booze, and John almost falls down the stairs of the secret passageway. He hears Owen's voice and feels some force pulling him up. Then, magically, John's hair turns white. Nothing like a little bit of added drama, huh? As the readers, we're held in suspense because we don't really know what we believe is true, but we read about these seemingly miraculous occurrences and have to figure out what to do with them.
Denouement
Everyone in town shows up for Owen's funeral.
Owen's funeral is characteristic of falling action (although, remember, in this novel we actually go to the funeral before we see how Owen dies). Everyone is there (well, almost everyone – Hester refuses to show up, just as she promised Owen when he was alive). We get the vibe that Owen's story is coming to a close – we just have to wait for Rev. Merrill to get in a few last words.
Conclusion
As an adult, John prays for Owen to return to him.
We know all the way through the novel that John now (that is, in 1987) lives in Toronto and tells us Owen's story from a distance of almost 20 years. Still, as far as we're concerned, he's mostly telling the story because it's an interesting one and the events that it covers have had a pretty big impact on his life. As the novel closes, though, we get a different sort of vibe. John prays to God to give Owen back to him (and, we suppose, everyone else who loved him). We get the sense that this is why John has been telling us the story all along; because he's trying to grapple with what happened to his closest friend and the effects that his death had on his own life. John's prayer at the end is sort of like the period at the end of a sentence – it wraps everything up for us.