A middle-aged person who’s thoroughly accustomed to their life of relative solitude is called upon, briefly or maybe for an indeterminate period of time, to caretake a child. That’s the animating premise of countless movies, and it is the basic synopsis of C’mon C’mon. The film from writer-director Mike Mills doesn’t upend any expectation in the details of the plot. All the beats anyone might expect are present: the initial moment of relative ease, the emergence of regular tests of the adult’s mettle, the emotional rollercoaster the comes with overseeing a small human bursting with curiosity and impulse and instinctual forthrightness. Like Jonathan Demme, the supreme humanist of U.S. cinema, Mills demonstrates that the quality of a film is defined less by the novelty of its storytelling particulars than the commitment to its empathetic truths. That’s not to imply that C’mon C’mon is absent invention. There are little flourishes throughout it, none more charming than the chryons that appear as graphic footnotes to inform the viewer which books are being read by the characters on screen. They key is that those flourishes resolutely enhance the humanity of the piece rather than stand as impish tinkering with form for their own sake. The main character, Johnny (Joaquin Phoenix, marvelous and understated), is an audio journalist with a specialty of interviewing kids about their general world views. The occupation makes for a nice parallel to the situation he finds himself in, looking after his nine-year-old nephew (Woody Norman), and it further speaks to Johnny’s openness to hearing and knowing those around him, including his young charge and his sister, the boy’s mother, played with depth and emotional acuity by Gaby Hoffmann. The film adheres to that principle of understanding. Mills wants us to truly, deeply know those he carries through this fiction, and it’s a mark of his achievement that they occasionally share the screen with real people, the subjects of Johnny’s recorded interviews, and they seem no less authentic for the comparison. C’mon C’mon is wise, warm, and absolutely wonderful.