In order to answer this question, we first have to understand what a plot is. Fiction can be broken down into two parts, plot and story. Plot is physical and story is emotional. Plot is what happens to your characters while story is what happens inside your characters. You can have a strong story and what some might consider a weak plot and still have a successful piece of writing. If you have a strong plot with a weak story or characters, it will appear wooden, two-dimensional and dull.
What is a weak plot? "Joe has to go down to the corner store and buy a loaf of bread for his mother." On the surface, this would appear to be a weak plot. However, suppose Joe's mother needs the bread to make stuffing for Thanksgiving dinner and Joe will see all his favorite relatives again. Also suppose that stuffing is Joe's favorite part of that dinner. Now we have an emotional tie to Joe getting the bread.
On the way to the store, Joe either confronts or has to avoid some of the school bullies that hang out in front of the store. We now have an additional conflict to Joe achieving his goal. How will he get in the store with his money still in hand? How will Joe buy the bread and get back home without getting beat up in the process. That is all plot. What makes the tale come alive is what Joe is going through in order to buy the bread.
End to end car chases or fights will not create a memorable plot. They are simply actions strung together to make a highlight reel. To create a strong plot the physical actions your characters are taking must have some meaning to your characters. Are your characters emotionally tied into what they are doing?
In Dan Brown's The Lost Symbol, Robert Langston's good friend Peter Solomon is kidnapped. Langston's motivation throughout is to save his friend. The plot is composed of all the twists and turns on the way to this emotional goal. If this had simply been a "treasure hunt", the novel would not have had any emotional impact.
Alfred Hitchcock used the term "mcguffin" to describe a plot device. He said it did not matter what the mcguffin was, it was simply that one thing everyone in the story was after. In The Maltese Falcon by Dashiell Hammett, the mcguffin was the "black bird".
Plots don't need a physical thing as a goal. Plots can also revolve around people and their quest for reconciliation with a parent or loved one, or a quest for personal redemption.
To create a strong plot in your fiction, give your characters something meaningful to do.