Tim Robbins, Martin Landau, Marianne Jean-Baptiste and newcomer Harry Treadaway have joined the cast of Walden Media and Playtone’s “City of Ember.” Directed by Gil Kenan, “City of Ember” is currently shooting in Belfast, Northern Ireland. Playtone’s Gary Goetzman and Tom Hanks are producers, with John D. Schofield exec producing. Cast includes Bill Murray, Toby Jones and Saoirse Ronan. “Ember” is set to open in October 2008 through Fox and will be marketed by the Fox Walden joint venture. “Ember,” based on Caroline Thompson’s script, centers on an insular place where the only light comes from street lamps. As the power source begins to fail, two teens search for clues that will unlock ancient mysteries about the city. Robbins will portray an inventor harboring a secret, Treadaway his teenage son.