As a filmmaker working on a large canvas in a quasidocumentary style, Mr. Affleck rises to one challenge after another with a sure touch. (And with the help of such collaborators as the cinematographer RodrigoPrieto, the production designer Sharon Seymour, the editor William Goldenberg, and Alexandre Desplat, who did the original score.) Tony's crash program to teach his six frightened charges their assigned roles feels convincing and fresh.