Despite the fact that Franco will be mainly playing off the troublesome rock, and his fizzog will be very much front and centre, Boyle and co have still managed to cram a few interesting faces into the pic to give Franco some back-up.

Clémence Poésy, the French actress seen in Harry Potter and the Goblet of Fire and In Bruges will play Ralston's lover, and True Blood's Lizzy Caplan is Ralston's sister Sonja. It's not yet known whether the movie (like Ralston's autobiography) will oscillate between the canyon confinement and flashbacks to the past, or whether we will be stuck with Ralston throughout his entire struggle.

Caplan doesn't give much away: "I play his sister. But a lot of the movie is James Franco dealing with his arm being trapped by a boulder."

Also joining the cast are Amber Tamblyn and Kate Mara as fellow hikers that Ralston meets early on his journey (they get a fair amount of screen time in the trailer), who could prove to be the final faces he sees (apart from his own recorded monologues to his video camera).

Treat Williams is also showing up as Ralston Sr, but don't expect any of these guys to nab a huge amount of screentime, as Boyle is primarily concerned with putting Ralston's experience right at the forefront.