Don’t let the name fool you: “April” is a wintery affair. By far the most uncompromising vision to play at this year’s Venice Film Festival, director Dea Kulumbegashvili’s slow cinema horror show might also be the most audacious. That audacity translates less by way of length or provocation – Brady Corbet’s “The Brutalist” and Harmony Korine’s “Baby Invasion” have those laurel locked up – than by way of self-assurance, from the filmmaker’s steadfast belief in her own creative gambit to her audience’s willingness to immerse themselves within.

This is, in so many words, a swing for auteur enshrinement so crystalline in intent that it namedrops Mikhail Kalatozov’s “The Cranes Are Flying” and visually cites Jonathan Glazer’s “Under the Skin” from the very jump.

Kulumbegashvili can reasonably wager on her film’s long-term prospects once it meets the right crowd, but the diverging festival...