#1. Start with a bang
Look, we have no time to waste. They say millennials have no attention span, but I think that’s applicable to all of us. Bird Box doesn’t waste a minute to start the action. As the movie opens the apocalyptic disaster gets rolling.
#2. Weave in a mystery
If you want an simple (not easy) way to carry your audience along, you can always thrown in a big mystery. This is the trick/formula of thrillers, horror, some adventure and definitely mystery movies and books. In Bird Box, everybody starts killing themselves and we have no idea why. Answering that question becomes the goal of the movie (and surviving it too, of course), and is the engine for our attention.
#3. Survival is a great motivation
In creative writing classes they tell you to give your main character a goal. What is it that they want? Make it clear and have the hero fight to get it. Well, let me tell you survival is the #1 motivator for anybody. If your hero is fighting for their life against an antagonist force (monsters, earthquakes, terrorists, etc), you have found the best . They say fear is a powerful motivator, and fear of death is probably the very best.
#4. Drop clues
This trick is specially useful if you don’t want (or can’t) resolve your mystery by the end of the story. I won’t spoil the movie, but the ending is not clear, and the cause of the disaster is never fully explained. In order to avoid disappointing their audiences because of an unresolved conflict, Bird Box drops some hints as to what is the answer. There are two characters who speculate and explain what is causing all the deaths. These explanations, although unconfirmed, are consistent with the story and provide a sense of closure. This is great for movies that don’t want to show the “monster” or stories that have such a convoluted mystery that there is no plausible explanation and therefore is better to leave unexplained.