>Heading toward its third-season finale Nov. 8, the AMC series remains TV’s most mesmerizing, anxiety-inducing show, largely because of its weirdly still, stiff performances. Most glacial of all is January Jones as resentful housewife Betty Draper. A ravishing cool blonde, Jones suggests Grace Kelly having a discreet crack-up in the ladies’ lounge. But when Betty at last uncovered the truth about husband Don (Jon Hamm), you sensed an angry, tectonic shift beneath the unyielding surface. Something may finally break.