“Chapter 5: Dig Dug” is chock full of amazing and intriguing gems, making me extremely curious as to how it will all end. The vines of the “upside down” are just the tip of the proverbial iceberg as we saw Sheriff Jim Hopper (David Harbour) dig a massive hole in the pumpkin patch and jump into a series of underground tunnels at the end of “Chapter 4: Will the Wise.” What is the “shadow monster” trying to accomplish in Hawkins?