Invented in 1887 as a “universal language” to facilitate global communication, Esperanto never went much of anywhere. Nonetheless, the creators of 1966’s feature film Incubus decided to use it for the movie’s dialogue.

The village of Nomen Tuum possesses a well which can perform various miraculous actions that entices a wide variety of parties to come. The town also acts as a home for demons and succubi.

This crop of sinful visitors acts as easy pickings for succubus Kia (Allyson Ames) and she tires of these activities. When she goes after the virtuous Marc (William Shatner), however, she encounters a challenge that leads to a battle for his soul.

When people remember Incubus, it seems like they recall it for two possible reasons. Some think of it as a movie which features a weird little-known language, whereas others view it as a movie which features a weird little-known language that Shatner made right before he landed the lead on Star Trek.

Not that many think of Incubus at all. The flick barely received any theatrical distribution in the 1960s so it essentially went unseen until it got a DVD release in 2001.

Some might want to view Incubus as a lost classic. Don’t count me as part of that potential crowd.

Not that I think Incubus becomes the silly mess I anticipated. I admit that the choice to use Esperanto for the dialogue implied to me I’d find a goofy and amateurish affair.

Instead, Incubus remains wholly professional. While mainly known for TV work, writer/director Leslie Stevens enjoyed decent talent, and cinematographer Conrad L. Hall would eventually win multiple Oscars.

Indeed, the photography of Incubus becomes its most outstanding feature. Hall uses the atmospheric black and white imagery to solid effect.

Though clearly heavily influenced by Ingmar Bergman, Incubus also comes with a more than serviceable plot. The basic battle for Marc’s soul comes with ample potential for drama.

Unfortunately, after a pretty good start, Incubus can’t do much with its theme. Once it establishes the succubi and their actions, it becomes mired down in tedium.

Really, Stevens just didn’t generate enough material for a feature film, even one with such a brief running time. Perhaps if Incubus got designed as a 45-minute TV episode, it might’ve formed a more dynamic end product.

As it stands, however, Incubus tends to plod and meander after its first act. The story and characters simply lack much to involve the viewer, so the film turns into a slow ride.

It does seem fun to watch an effort from a pre-Trek Shatner. Of course, Shatner had been a working actor for many years, most notably in 1961’s Judgment at Nuremberg and the classic 1963 Twilight Zone episode “Nightmare at 20,000 Feet”.

Nonetheless, Incubus offers our final glimpse of Shatner before Trek would irrevocably alter this life and career. He overacts as usual, but he still adds some spark to the proceedings.

Too bad Shatner doesn’t bring enough flair and charisma to make Incubus a consistently compelling journey. Though it comes with positives, the end result seems fairly dull.

Incubus appears in an aspect ratio of approximately 1.85:1 on this 4K UHD Disc. Though the Dolby Vision image showed the restrictions of its source, it nonetheless held up fairly well.

Softness became a moderate concern, as wider shots leaned a bit soft. Still, most of the film came with pretty positive delineation.

No issues with jagged edges or shimmering occurred, and I saw no edge haloes. Grain seemed moderate and print flaws remained absent.

Blacks seemed decent, if a little inky, and the movie leaned somewhat too bright much of the time. HDR did intensify whites and contrast. Though something of a mixed bag, the film still offered largely appealing visuals.

The LPCM monaural soundtrack of Incubus seemed perfectly fine for its age and scope. Speech lacked warmth but always came across as clear and intelligible.

Effects were clean and distinct despite some thin tones. Music showed a similar lack of heft but the score lacked distortion or shrillness. This turned into an adequate track.

How did the 4K UHD compare with the Blu-ray edition? Both offered identical audio.

As for the UHD's Dolby Vision image, it offered moderate improvements in terms of sharpness, blacks and contrast, though it also made grain more prominent. I preferred the 4K UHD but the limitations of the source restricted its ability to upgrade the visuals.

As we move to extras, we find three separate audio commentaries. The first comes from producer Anthony Taylor, cinematographer Conrad L. Hall and camera operator William Fraker, all of whom sit together with moderator David J. Schow for a running, screen-specific discussion of photography, sets, and various aspects of the production.

Created for the movie’s 2001 DVD release, this becomes a largely mediocre commentary. While we learn a decent array of filmmaking notes, the overall chat seems spotty and without a lot of insight.

Also taped for that 2001 DVD, the second features actor William Shatner. He brings a running, screen-specific view of how he came to the production, cast/crew, working in Esperanto and general production memories.

Expect a screen-specific chat only in the loosest sense. While Shatner does watch the film as he remarks, he only sporadically reacts to what he sees and he almost never actually discusses the film as it unfolds.

On the positive side, Shatner gives us some good memories of the shoot. On the negative side, his notes pop up infrequently, and that leaves us with an awful lot of dead air.

In addition, Shatner tosses out some very dry – and not especially funny – stabs at humor, most of which revolve around lies about the production. We do find some worthwhile info from Shatner but not much, and the commentary’s flaws make it a tough listen.

Recorded specifically for this 2025 release, the final commentary comes from film historian David J. Schow. He delivers a running, screen-specific view of cast and crew, different iterations of the script, aspects of the production, the movie’s release and subsequent history, attempts to find a copy of the film, and related areas.

Schow packs a lot of information into the flick’s brief length. I think he probably spends too much time with details of the phony screenplay the filmmakers gave to those who run a mission used as a location, but otherwise, this turns into a solid examination of Incubus.

The movie can also be watched with an Isolated Score Track. This presents Dominic Frontiere’s music via LPCM stereo sound.

Another alternate viewing option comes via an Open Frame Presentation. Unsurprisingly, this 1.33:1 version reveals more image at the top and bottom of the frame.

It also means burned-in French subtitles from the print become obvious. We occasionally slivers of that text in the 1.85:1 version, but the cropping usually removes them.

Other than the presence of those French subtitles, the “open matte” and 1.85:1 editions look identical. Of course, they come with the same audio as well.

In addition to a video trailer, three video programs complete the set. Words and Worlds spans 43 minutes, 20 seconds and offers notes from genre/comic book historian Stephen R. Bissette.

“Worlds” discusses the history of Esperanto and its use in movies and other media. Bissette spends too much time on his own experiences but he still delivers a generally good take on the topics, even if he repeats some Incubus-specific info we hear elsewhere.

Internacia Lingvo goes for 22 minutes, five seconds. It brings remarks from linguist Esther H. Schor.

Here we find details about the history of Esperanto and aspects of its development. Schor finds a different approach to the subject than Bissette did so that makes her remarks useful.

Finally, we get a 2001 featurette simply called An Interview with the Makers of Incubus. The 19-minute, 15-seconds piece includes a chat among Schow, Taylor, Hall and Fraker.

They talk about the project's development as well as their work on it and related domains. Though this inevitably duplicates some content from their commentary, it nonetheless turns into a tighter discussion than that lackluster piece.

As one of very few movies that used Esperanto dialogue, Incubus exists as little more than a curiosity. While the movie does offer good photography and a potentially compelling narrative, the end result feels too sluggish and flat to go anywhere. The 4K UHD offers generally positive picture and audio along with a nice array of bonus materials. Tough not a terrible movie, Incubus also fails to come across as anything interesting.

To rate this film, visit the BD review of INCUBUS