The 2007 drama, which chronicles the notorious San Francisco slayings of the late 1960s, is more than just another serial killer thriller from the director of "Seven" -- it's a meditation on the pursuit of truth, a quest that sometimes goes frustratingly unfulfilled. "Zodiac" also marked a career highlight for its trio of sleuths, played by Jake Gyllenhaal, Robert Downey Jr., and Mark Ruffalo, a cast that would be difficult to assemble today without a truckload of cash and some superhero costumes.