Audiences have returned to Pandora almost a decade and a half after our first visit to James Cameron's "Avatar." The sequel takes place 14 years after the original film, and Jake Sully (Sam Worthington) and Neytiri (Zoe Saldaña) have a family of both biological and adopted children. Since most of the humans left Pandora, there have been years of peace. Now the RDA (Resources Development Administration) has returned, with Colonel Miles Quaritch (Stephen Lang) in a Na'vi avatar (it's complicated). Earth is dying, and there are riches to exploit here. You see where this is going.