We haven’t heard much about Paul, starring Simon Pegg and Nick Frost since way back in September. Now, Universal Pictures has released the official synopsis for Greg Mottola‘s upcoming sci-fi road trip movie that opens on March 18th of next year. In addition to Pegg and Frost, the film also stars Seth Rogen (voicing the alien title character), Sigourney Weaver, Jason Bateman, Kristen Wiig, Bill Hader, Blythe Danner, Joe Lo Truglio, John Carroll Lynch and David Koechner.

via Working Title

Simon Pegg and Nick Frost (Hot Fuzz, Shaun of the Dead) reunite for the comedy adventure Paul as two sci-fi geeks whose pilgrimage takes them to America’s UFO heartland. While there, they accidentally meet an alien who brings them on an insane road trip that alters their universe forever.

For the past 60 years, an alien named Paul (voiced by Seth Rogen) has been hanging out at a top-secret military base. For reasons unknown, the space-traveling smart ass decides to escape the compound and hop on the first vehicle out of town—a rented RV containing Earthlings Graeme Willy (Pegg) and Clive Collings (Frost).

Chased by federal agents and the fanatical father of a young woman that they accidentally kidnap, Graeme and Clive hatch a fumbling escape plan to return Paul to his mother ship. And as two nerds struggle to help, one little green man might just take his fellow outcasts from misfits to intergalactic heroes.

Paul is directed by Superbad’s Greg Mottola, from a story by Pegg & Frost. Joining the comedy’s cast are Jason Bateman, Kristen Wiig, Bill Hader, Blythe Danner, Joe Lo Truglio, John Carroll Lynch, David Koechner and Sigourney Weaver.

Paul is slated to hit theaters on March 18th, 2011