The episode, titled "Lost in Danville," was originally announced at Comic-Con International: San Diego, and is written by Lost co-creator Damon. Terry O'Quinn, who played John Locke on Lost, will voice the evil scientist, Doctor Mystery.
Taking a cue from Lost, the episode centers on a mysterious capsule that falls into Phineas and Ferb's backyard. Naturally, bad things happen after they open it.
The episode also features guest voice stars Jane Kaczmarek (Malcolm in the Middle) and Rob Morrow (Numb3rs), who the capsule's passengers, Denise and Bernie.
Also, there is Polar Bears.