Janey, the 13-year-old protagonist and occasional narrator in “Rain,” tells us her family’s summer home was right on the beach — well, with just a small patch between it and the beach. Also, “it was sunny … mostly.” In other words, things were nearly perfect, but not quite. But close!

In fact, things are bad and getting worse in this evocative, moody drama from first-time New Zealand director Christine Jeffs. Janey, played with extraordinary perception and sensitivity by new-comer Alicia Fulford-Wierzbicki, is caught between childhood and adulthood, romping in the surf with her little brother Jim (Aaron Murphy) one minute, serving drinks (and taking swigs herself) at her parents’ party the next.

It is set in the ’70s, which one gathers was quite a swingin’ time in New Zealand. The parents, Kate (Sarah Peirse) and Ed (Alistair Browning), have a failing marriage fueled by Kate’s alcoholism and her flirting with Cady (Marton Csokas), a nearby boat-owner/photographer. One suspects the many, many beach parties are to distract Mom and Dad from their problems, and from each other.

Janey, alas, has learned sexual aggression from Mom, and the consequences of her growing up while her parents grow apart are tragic indeed. Her post-encounter shower is quite different from her mother’s, seen earlier in the film, having been colored by heartbreak and turmoil.

Jeffs’ cinematographer John Toon has an eye for vivid composition, as in the memorable scene of Kate wading back to shore after visiting Cady’s boat. The entire film is awash in sepia tones, befitting a film set in the ’70s. Mood is key here, and the mood is strong.

Jeffs herself, who adapted the film from Kirsty Gunn’s novel, has a good way with actors, too, coaxing marvelous performances from all five lead actors. Alistair Browning’s weary, defeated father; Sarah Peirse’s in-denial mother; Marton Csokas’ caught-in-the-middle paramour; Aaron Murphy’s unsupervised little boy; and especially Fulford-Wierzbicki’s confused, self-assured adolescent — all rich portraits in a film that recognizes the importance of character and the powerful impact of imagery.

B+ (1 hr., 28 min.; R, a little profanity, a scene of skinny-dipping with visible nudity, some sexuality.)