The good news is that a fifth Indiana Jones film is still in the works. The bad news is that no one's sure exactly how long it's going to take to see the light of day. Although Steven Spielberg recently told Entertainment Weekly that he and George Lucas had decided on a genre for a fifth adventure, Vulture caught up Lucas last night and learned that the story is still missing a crucial element: the MacGuffin.

"I mean, I know what it's about," Lucas said, "but I just have to find a MacGuffin that fits into the arena we're working in."

A term popularized by Alfred Hitchcock, a MacGuffin refers to a narrative element that drives the story forward. The Indiana Jones series is famous for making the MacGuffin the object of Dr. Jones' search. In the first film, it's the Ark of the Convenant, the second the Sankara Stones, the third the Holy Grail and the most recent the Crystal Skull.

(Photo Credit: PNP / WENN.com)