Jessica Chastain gives one of the gutsiest performances of her career in Michel Franco’s “Dreams,” here as a San Francisco philanthropist in love with a younger, undocumented Mexican immigrant who she’s convinced to cross over into the United States.

Emotionally lobotomized by her wealthy scion father (Marshall Bell) and brother (Rupert Friend), Jennifer (Chastain) gives money to good causes and believes she’s contributing to some greater good. Meanwhile, Fernando, a 10-plus-years-younger ballet dancer from Mexico City, is at her every mercy trying to start a life in America after a harrowing journey over the border.

The characters may function metaphorically as stand-ins for the U.S. and Mexico and how those countries, like these people, need each other. But politics aside, what makes the “New Order” director’s latest film, and his second with Chastain after the dementia-addled romance “Memory,” throb and thrum beneath the filmmaking’s...