Buddy-cops Martin Riggs and Murtaugh are back, trying to keep a key witness-and themselves-alive in Lethal Weapon 2. And exciting it is, from its breathless opening chase through L.A. streets to its raging gun-battle finale. In between, there's a six-story plummet from a window, a booby-trapped toilet, a Houdini-like underwater escape and the incredible destruction of a chic hillside stilt house.