Sydneyfindsherselfface-to-facewithherlong-lostmother,IrinaDerevko,whoseintentionsforherdaughteraremadechillinglyclear.However,SydneymanagestoescapeandrejoinJackandWillintheirescapefromTaiwan.AfterarrivingbackinLosAngeles,SydneycontinueshersearchforVaughn,notknowingifheisdeadoraliveafterbeingsweptawaybyawallofwaterin...