Like their score for The Social Network, Trent Reznor and Atticus Ross’ Patriots Day soundtrack is a dark affair. On “Them and Us,” drums and guitar slowly build to a shuddering climax of swirling feedback, while the drones and arpeggios of “The Place You Are Right Now” suggest an anxiety-ridden approximation of trance music. But they can be gentle, too: In “We Forget Who We Are,” a contemplative piano melody quietly rises above hopeful strings—the acoustic silver lining to a heavy electronic cloud.