Starring Bel Powley and Kristen Wiig. Rated 18A.

A startlingly frank journey into the faraway life and times of a particularly adventurous adolescent, The Diary of a Teenage Girl concentrates on the kid’s own recollection of pretty thorny events.

The superbly acted film, which won the best-cinematography award at this year’s Sundance festival, is a dreamlike—and sometimes quietly nightmarish—evocation of youth.

That fits its origins as a graphic novel, and as girl-centric adaptations go, this is right up there with Ghost World and We Are the Best! (from Sweden’s Lukas and Coco Moodysson). But first-time writer-director Marielle Heller has a fiercer, less whimsical eye, despite the rococo decorations. And Brit newcomer Bel Powley (who’s actually 23) doesn’t bother to be overly ingratiating as Minnie Goetze, 15 and adrift in 1976 San Francisco.

Minnie already has a rivalrous relationship with her single mom, Charlotte (Kristen Wiig), who can’t seem to keep a job, or a dude, for very long. Mom’s latest beau is a handsome, genial hustler called Monroe (Sweden’s Alexander Skarsgård); his arrival on the scene, unfortunately for everyone—including little sister Gret­el (Abby Wait), who hardly figures in anyone’s plans—coincides with Minnie’s sexual awakening.

You can probably guess where that’s going.

Our seemingly mousy young heroine is a compulsive cartoonist and dreams of getting published like underground-comix hero Aline Kominsky, who makes an appearance in the film’s mix of animation, fantasy, and rust-brown realism. (This is the ’70s, after all.) Minnie’s Monroe fixation finds its way into sketchbooks and plainspoken updates on a portable cassette recorder, hence the potentially explosive diary of the title.

Today we would say she has body issues, but she also shows some confidence with boys at the relaxed private school paid for by her ex-stepfather (Christopher Meloni) and goes club-hopping with her savvy best pal, Kimmie (first-timer Madeleine Waters, who recalls the Scarlett Johansson role in Ghost World).

Heller treats all this with the same judgment-free attitude that Minnie brings to her diaristic endeavours, with just a few nods toward the hard-earned wisdom her subject will likely gain in hindsight. The results range from disturbing to heartbreaking and amusingly honest.

The only downside is a constant tone of low-level conflict that, if nothing else, can make you thrilled to never be 15 again.