Director John Patrick Shanley loves to deal with weighty philosophical themes, but thankfully he knows how to do so through three-dimensional characters that make his grand ideas a part of everyday life. Doubt, his adaptation of his own award-winning play, offers a crystalline example of his remarkable gifts. The film stars Meryl Streep as Sister Aloysius Beauvier, a no-nonsense Catholic middle school principal who watches over her students with steely eyes and a firm hand. She carries a simmering dislike for the popular priest Father Flynn (Philip Seymour Hoffman) because his easy rapport with the students clashes with her old-school style. After Flynn delivers a sermon that suggests doubt can bring people together as much as faith, Sister Aloysius wonders why a man of the cloth would ever seek refuge in questioning God. Believing Father Flynn may be hiding something, Sister Aloysius asks history teacher Sister James (Amy Adams) to inform her if Flynn exhibits any strange behavior. Not long after, Sister James discovers that one of her students, Donald Miller, smells of alcohol after paying a private visit to Flynn in the rectory. Armed with this information, Aloysius campaigns to drum Flynn out of the parish. Although she could rest on her laurels as a living legend, Meryl Streep is always eager to take up a new challenge, and Doubt gives her the meatiest role she's had in a very long time. She inhabits Sister Aloysius with a self-assurance and authority that dominate the screen, except when matched by Hoffman's formidable physicality. He imbues Father Flynn with an all-encompassing charm and ease that make it plain why his students adore him. Their battle with each other takes on a mythic Irresistible Force vs. Immovable Object quality. Like Sister Aloysius, we never see what transpires in the rectory between the boy and the priest, and because of this it's impossible to tell at any given moment who is right and who is wrong -- your sympathies vacillate between the two characters even after the story ends. However, those two are far from the only fascinating characters in the movie. The conflicted Sister James likes that Father Flynn expresses such kindness toward the students in general -- and one troubled boy in particular -- but Sister Aloysius is her mentor. Her struggle is one of the most obvious embodiments of the film's title. And Donald's mother, played to perfection by Viola Davis, leaves an indelible impression with very little screen time because her character radically changes the audience's perceptions of what's at stake when she reveals shocking information about the child's home life. But, for all the powerhouse acting, this is John Patrick Shanley's show, and he uses this movie to ask profound questions about belief and ethics. His final scene provides a genuine dramatic wallop that resolves the movie's central conflict, without answering these weighty existential questions. Because of this, Doubt satisfies the heart and engages the mind.