Introduction part is that one in which you can "gain" your readers or you can "loose" them. It is very important the way you choose to write the introduction, but is very important also to keep in mind that you can rewrite it whenever you want, till the end of the story. The path you find to construct your plot could be very useful to "design" your introduction of the story, cause the introduction could be seen like a map which giudes the readers to the subject. If the road is complicated, the readers will abandon it, loosing their interest, but if you guide them properly,with the help of introduction, they will be able to digest the subject as you've intended to.
Pay attention also to have a concise style, no errors in writing and give readers some powerful idea concerning your analytical skills, which they will meet lecturing your work and the quality of your story.