A dozen years after Seven, director David Fincher again treats a serial killer, only this time it’s a true story (adapted by James Vanderbilt from Robert Graysmith’s autobiographical best seller) and not at all metaphysical. In some ways, for better and for worse, this is even more about Graysmith (Jake Gyllenhaal)who became obsessed with solving the Zodiac killings that terrorized northern California in the late 60sthan about the murderer. I’m not convinced this had to be 158 minutes long, so it’s all the more annoying when essential material gets elided (as in a sequence featuring an uncredited Ione Skye). But Fincher does keep this bubbling along, ably assisted by a cast that includes Mark Ruffalo, Robert Downey Jr., Chloe Sevigny, Elias Koteas, and Philip Baker Hall. R. (JR)