Your novel is the dramatization of a story. So that means your plot will focus on the events and actions that best illustrate that story. Most stories have your A plot, which is you main storyline the goal driving your protagonist, and a B plot, which is a smaller plot that usually is at odds with the A plot. If the protag gets A, he loses B and vice versa. This provides extra conflict, usually internal. Plot A is usually external, plot B is typically internal. (and internal doesn't mean it's all in his head. It means his actions are at odd with his feelings on a subject) There are other setups but this is the most basic and quite effective.
Every scene in your story will advance one of those plots. The protag will be doing X to gain another step toward achieving the goal, or being pushed away from it. You can have tons of obstacles to reach either of those goals (which is the plot and bulk of your novel) but each obstacle will be there to build toward the resolution of the story and the achievement of that story goal. You won't have your protag stuck in a cave in unless being stuck in there advances the plot in some way. Maybe the protag is there because he needs to overcome his fear of the dark in order to fight the shadowy bad guy. Maybe he finds a secret way into the villain's lair. Who knows, but it need to be more than just "he gets stuck in a cave in and has to find his way out and exciting things happen."
When I plot, I keep my core conflict and end goal in mind. With every scene, I ask myself, "Does this advance one of my two core plot lines?" If yes, I keep it, if no I scrap it. Or I find a way to make it do that. And it doesn't have to be direct advancement. If the protag needs to rescue his wife, and he needs money to pay a ransom, then robbing a bank might be the goal to getting the money to save the wife. To rob the bank he needs to get equipment or information. Getting that could be another goal (and step) toward the larger end goal. The problems he runs into trying to get the gear to rob the bank to get the money to save the wife are all scenes of the novel, and they all advance the story of a man trying to save his wife from kidnappers.
Knowing that core conflict and end goal is critical, or you can wander off and find yourself stuck. That's what the one-sentence pitch line is great for. It reminds you about the protag, antag, problem and stakes. It doesn't have to be agent-worthy, but it needs to be clear enough to show exactly where the protag is going, why he's going there, who's trying to stop him, and what's at stake if he fails. If you don't know those four things, you're not ready to write the story yet. You have a premise, but no actual story.