If you are late to see this amazing video, it's a great place to begin. J.J. Abrams is a Master Storyteller and he utilizes the "Mystery Box," in such a crazy cool way. It's a small element you keep hidden from the audience to keep them excited and engaged with the content. You only reveal what's inside the box at the very last possible moment, or in some cases, it is never revealed at all.
This Ted Talk has been around a bit, but it is worth the time investment.