What is a plot? It’s a sequence of events, with one special property.
A sequence of events is this happened, then that happened. A plot is this happened, then that happened, because.
Some say there are three basic plot engines:
- Person against nature
- Person against person
- Person against God
“Person against person” includes as a sub-group “person against self.”
Some say there are five basic plot engines. They are:
- The brave little tailor
- If this goes on
- The person who learned better
- Who am I?
- How do we get home?
Dickens’ classic A Christmas Carol is an example of “The person who learned better.” Dickens’ story has such a strong plot engine that it’s survived everything from Mr. Magoo to the Muppets.
Some folks add “Reader, I married him” to the list. Others add “A person leaves town” (and its inverse, “A stranger comes to town”).
I like to say that the oldest engines pull the heaviest freight.
JAMES D. MACDONALD 
There’s also “Who are these people and why are they shooting at me?”, which can be combined to good effect with #4 or #5, with a bit of #1 thrown in for reader identification.
…The ever-popular “Who are those guys?”