The secret behind Kate's past may be revealed when a sealed briefcase is found -- and Kate (Evangeline Lilly) isn't about to let anyone open it, least of all Sawyer (Josh Holloway). In flashback, we learn more about Kate's checkered past. In other developments, a pouty Shannon (Maggie Grace) won't use her knowledge of French to help Sayid (Naveen Andrews) decipher a mysterious missive. With Claire (Emilie de Raven) still missing, an unlikely friendship begins to develop between Charlie (Dominic Monaghan) and Rose (L. Scott Caldwell). And the plane's remaining fuselage may disappear without a trace as the result of an unpreventable force of nature.