In a committed, near-silent performance, Robert Redford plays a man struggling to stay alive after his boat goes adrift in the Pacific Ocean. Writer-director J.C. Chandor (Margin Call) presents the character’s survival efforts in precise detail and unwavering focus; in fact this sometimes feels like an instructional film about self-preservation at sea. The unsentimental tone is refreshing after the mawkishness of Ang Lee’s Life of Pi, yet something is missing—a sense of Redford’s social position, maybe, or other details that might better individualize him. This is gripping as an adventure story even if doesn’t achieve the profundity to which it aspires.