While the FBI detains and questions Sydney about her past and possible ties to a mysterious Rambaldi doomsday prophecy, Vaughn and Jack must race to free her and find a way to clear her name before her cover is blown and SD-6 is made aware of the situation. Once the rescue op has been launched, in her quest to prove her innocence, Sydney shocks even her usually unflappable father when she makes a chilling discovery that may unravel the mystery of the 500-year-old prophecy