Based on his performance in the NC-17 rated Shame, it was clear that Michael Fassbender is not averse to taking on challenging roles. But even so, his performance in Frank may take viewers by surprise. For the entire movie, Fassbender wears a giant papier-mâché mask over his head and at no point in the film does the viewer ever get a chance to see Fassbender’s face.

Since facial expressions are a key aspect of acting, you’d think that wearing a giant mask over his head would place enormous restrictions on Fassbender’s ability to do his job. But as the new trailer reveals, his character is able to get around this by verbally announcing his facial expression. “Welcoming smile,” he’ll say, or “wear a grin,” or “bashful half smile.”

The film also stars Domhnall Gleeson, who by this time next year will likely be one of the most famous actors in the world, thanks to Star Wars: Episode VII.  Gleeson plays a young musician who joins a band called the Soronprfbs, which is led by Fassbender’s Frank. Undeterred by Frank’s obvious mental illness, Gleeson convinces the group to perform at South by Southwest.

The movie is loosely based on the late British musician Chris Sievey, whose Frank Sidebottom persona wore a similar mask.

Frank hits theatres August 15.