In John Q., Denzel Washington starts taking hostages when a hospital denies his son a heart transplant. And you may feel like he's taken you hostage, too, so powerfully does he summon up the frustration many of us feel with the health-care system in this country. The movie can hardly be said to play fair; Anne Heche and James Woods seem to have misplaced their own hearts. But on its own manipulative terms, John Q. is a nice piece of work. Director Nick Cassavetes knows just how to push our buttons, tossing in a joke or two whenever things start to get too heavy. And the movie is expertly edited by the great Dede Allen. There are moments when the whole thing plays like one of those '30s agitprop plays where the audience spontaneously jumps to its feet and shouts "Strike!" But John Q. has something that many of those plays didn't have: heart.