When summarizing the of a plot, it's important to be selective about which details are included. As Michelangelo supposedly said, "I have taken a block of marble and cut away everything that was not David." The same can be applied to writing a plot summary. The goal is to be as succinct as possible without sacrificing a clear understanding of the story.
Begin your summary by discussing the exposition, or introduction of the story. The exposition should introduce the protagonist and his or her problem and set the stage for what is to come. During this part, it's also good to make notes of the essential characters and events in the story.
Then, shift the focus to the inciting incident, or what changes the direction of the story. This is usually a key event that sparks the central conflict in the novel. As the story progresses, the inciting incident is followed by rising tension that builds until it comes to a climax.
The climax is often the most pivotal point in a story. It may change how a character behaves or even alter the future of the entire work. For example, the climax of Shakespeare's "Romeo and Juliet" is the death of Tybalt, which leads to a symbolic end of the feud between the two families. It may also encapsulate social change brought about by tragic loss.