Sigourney Weaver has read the scripts for all five Avatar movies planned out by director James Cameron, and she says viewers can expect 'a huge story' as the epic franchise unfolds.The 73-year-old star played the ill-fated human scientist Dr Grace Augustine in Avatar, but returns this time around as Kiri — the adopted teenage daughter of Jake (Sam Worthington) and Neytiri (Zoe Saldana).Avatar: The Way of Water is in UK IMAX and cinemas from 16 December.