After making a shocking discovery in the desert, Sydney agrees to submit to an experimental procedure conducted by an eccentric doctor, designed to retrieve her lost memories. But while Jack and Vaughn look on, Sydney's mind proves surprisingly resistant to letting her remember her missing time -- and the process of recovering it could end up killing her. Meanwhile, Lauren makes a great sacrifice in order to make her alibi believable to Lindsey after breaking Sydney out of NSC custody, and Sloane finds himself boxed in by an unlikely enemy -- one who wants to see Sydney Bristow eliminated permanently