It’s been 19 years since Harrison Ford, wearing his distinctive hat, galloped into the sunset with Sean Connery in Indiana Jones and The Last Crusade. Now the famous archaeologist is back in a fourth movie, Indiana Jones and The Kingdom of the Crystal Skull. A recently released trailer looks fantastic, and hints that Indiana Jones is heading into uncharted territory, with a possible science fiction element added to the usual adventurous mix. If you watch carefully, half way through the trailer, you’ll see a close up of some words on the side of a jeep which read: “Roswell, New Mexico, 1947”.

In Roswell, New Mexico, on 7 July 1947, conspiracy theorists believe the US Government retrieved and then hid an alien spacecraft that had crash-landed in a farmer’s field. The US Government has always maintained it was merely a weather balloon that had fallen to Earth and broken apart.

You can watch the trailer here on Indiana Jones' official website.

The movie reunites Harrison Ford with executive producer George Lucas and director Steven Spielberg. Whether or not Indiana Jones battles aliens, Lucas revealed there will definitely be some science fiction content.

“We’re doing a B Science fiction movie from the ‘50s,” he said in a recent article in Vanity Fair. “The ones I’m talking about are, like, ‘The Creature from the Black Lagoon,’ ‘The Blob’, ‘The Thing’.

The movie’s title is based on actual crystal skulls that were once displayed in museums across the globe, originally thought to be proof of ancient Mayan grinding technology. Even though discovered to be fakes, most likely manufactured in Germany in the late 19th century, some New Age believers still credit them with magical powers.

“The theory is they are shaped by higher powers or alien powers or come from another world,” producer Frank Marshall explained.

Short snippets half way through the trailer show Indiana being chased through what looks like a storage facility. Could this be the same storage facility where the Ark of the Covenant was stored at the end of the first movie, The Raiders of the Lost Ark? Perhaps an alien spacecraft is stored there too?

This time around the action has moved to the middle of the Cold War, with Indiana 19 years older. The last movie was set in 1938 before WWII and this one in 1957, which nicely accounts for an older Harrison Ford in real life: the last movie was released 19 years ago in 1989.

While searching for the Crystal Skull, Indiana Jones battles agents of the Soviet Union, led by Spalko, played by Cate Blanchett. Even though they couldn't coax Sean Connery out of retirement to reprise his role as Indiana Jones’ father in the last movie, Karen Allen, the actress who played Indiana Jones’ lover in the first film, The Raiders of the Lost Ark, makes a welcome return as Marion Ravenwood.

Ray Winstone appears as Mac, both a friend and a competitor, and John Hurt plays Abner Ravenwood, Marion Ravenwood’s father.

The story idea came from George Lucas and the final screenplay from David Koepp. Various writers have produced draft scripts for the movie (including M. Night Shyamalan, most famous as writer and director of The Sixth Sense) apparently because George Lucas and Steven Spielberg were never completely satisfied. David Koepp used what he thought were the best parts of each draft to create the final work.

An alien encounter may be just what Indiana Jones and The Kingdom of the Crystal Skull needs to top the discovery of the Holy Grail in Indiana Jones and The Last Crusade. It’s been a long time, but hopefully they can capture the magic of the original movies, and maybe even surpass it.

You can view the official Indiana Jones and The Kingdom of the Crystal Skull movie poster here.

Shooting was in June 2007 and Indiana Jones and The Kingdom of the Crystal Skull is set for worldwide release on May 22, 2008