Ira Sachs’s ambitious and intense depiction of the fraught relationship between a literary lawyer with substance abuse issues and a documentary filmmaker is one of the most honest and moving films in years. When they hook up in 1990s New York City via a phone sex line, Eric is attempting to make a film about underground figure Avery Willard while Paul is a closeted professional who smokes crack casually. Their initial encounter evolves into something more serious; unfortunately, so does Paul’s drug habit. Taking the couple through nine years involving rehab, infidelity and break-ups, Keep the Lights On is deeply personal, drawn from Sachs’s own experiences.

Through this autobiographical prism, the film refracts powerfully to convey a larger and revelatory lesson about the secrets people keep. After Paul heads to counseling, Eric’s best friend wonders why she was told nothing about the problem and he confesses, “I’ve been hiding crucial events in my life since I was 13.” This film’s remarkable frankness is a potent rejoinder to this statement, a plea to all marginalized communities to speak up and tell their stories no matter how painful.

Daring in its depiction of gay sexuality, powerfully acted by Danish Thure Lindhardt (Brotherhood, Frameline33, and Flame and Citron) as Eric and Zachary Booth as Paul, the film benefits also from the melancholy folk-disco soundtrack featuring Arthur Russell and Thimios Bakatakis’s luminous cinematography. Regarding the latter, notice particularly how light shines on Eric at different moments and in different ways — illumination may be out of reach for him, indeed for many of us as we grope our way through life, but it’s definitely, and defiantly, within the grasp of Mr. Sachs’s brave and inspiring film.