"A Tale of Two Cities" is the third season premiere, and 50th episode overall, of the American Broadcasting Company (ABC)'s serial drama television series Lost. The episode was written by co-creators/executive producers J. J. Abrams and Damon Lindelof, based on a story by Lindelof and directed by executive producer Jack Bender. The episode begins with the introduction of Juliet Burke and The Barracks. The character of Jack Shephard is featured in the episode's flashbacks. This is the only episode of the series other than the pilot to have been co-written by J. J. Abrams.

The third season of the American serial drama television series Lost commenced airing in the United States and Canada on October 4, 2006, and concluded on May 23, 2007. The third season continues the stories of a group of over 40 people who have been stranded on a remote island in the South Pacific, after their airplane crashed 68 days prior to the beginning of the season. In the Lost universe, the season takes place from November 28 to December 21, 2004. The producers have stated that as the first season is about introducing the survivors and the second season is about the hatch, the third season is about the Others, a group of mysterious island inhabitants.