Based on the ABC description for "Ab Aeterno," this is all we know about next week's Lost episode: Richard faces a difficult choice.

But it certainly sounds like we're gonna get the long-awaited Richard flashback episode. How come? Check out the following list of guest stars and the characters they'll portray:

• Mark Pellegrino as Jacob
• Titus Welliver as man in black
• Mirelly Taylor as Isabella
• Steven Elder as Jonas Whitfield
• Juan Carlos Cantu as Father Suarez
• Izzy Diaz as Ignacio
• Davo Coria as servant
• Santiago Montone as prisoner
• Sonya Masinovsky as Russian nurseSo

Who, who, who... and who?!? The following photos, also taken from "Ab Aeterno" make it clear that Lost viewers will be introduced to new characters and an old era:

Check out a pair of clips from the episode below - and don't forget to sound off on our Round Table discussion of "Recon."

[video url="http://www.tvfanatic.com/videos/jacob-and-ilana/" title="Jacob and Ilana"] [/video]

[video url="http://www.tvfanatic.com/videos/lost-sneak-peek/" title="Lost Sneak Peek"] [/video]

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.