The most mind-blowing, series-changing cliffhanger in any J.J. Abrams series, season two of Alias concluded with an epic showdown between Sidney and evil Francie doppelganger Allison Doren that left the hero unconscious in her burning apartment. When she woke up, she was wearing different clothes and lying in a street in Hong Kong. The mystery continued as she phoned for help and was visited by her lover Michael Vaughan. Keen-eyed audiences noticed he was wearing a wedding ring before Sidney, but that wasn't the only surprise. Two years had passed since that fight and she had been presumed dead. Once people got over the jaw-dropping shock of that moment, they were left us with a million questions. What had happened to Will, last seen bloody and unconscious in the bath? What had happened to Sloan and her mother, the traitorous Irina? Who was Michael's wife? And just where the hell had Sidney been for two years? More importantly, why didn't she remember any of it? A truly great cliffhanger leaves audiences a truly gasp-worthy moment, lots of questions and an anticipation for the next season. The season two cliffhanger to Alias did that all and was truly one of the greatest season finales of all time.