This paragraph narrows down the topic area of the paper. If you can't "sell" your work at a high level in a paragraph in the intro, then you are in trouble.
For example, "Our results are both theoretical and applied in nature.
(two sentences follow, one each on theory and application)" Paragraph 4: At a high level what are the differences in what you are doing, and what others have done?
Use this list to make sure you've included all of the most important things, including some of the following: This will demonstrate that you are actively engaging with the topic and understand it.
For example, if your question is: “Discuss recent developments in VR technology” you could include a sentence such as: “This essay will consider contemporary developments in the field of virtual reality over the past 5 years..." These sentences belong at the beginning of paragraphs and sum up the sense of the paragraph as a whole.