LONDON — In his first movie role since “Billy Elliot,” teenage Jamie Bell has started shooting the untitled war project for debut writer-director Michael J. Bassett.

Pic, lensing in Prague, tells the story of a group of young Brit soldiers in WWI who get cut off in a captured German trench and start falling victim to a mysterious assassin who turns out to be far from human.

Bell’s co-stars include Andy Serkis, who plays Gollum in the upcoming “The Lord of the Rings: The Fellowship of the Ring”; Hugh O’Connor (“Chocolat”); and Matthew Rhys.

It’s the first film from new U.K. production outfit Film and Music Entertainment, a partnership between Germany’s Fame and Brit producers Mike Downey and Sam Taylor.

Pic is being co-produced by Potsdam-based Apollo ProMedia.