Messiah of Evil is part of a horror tradition that we almost never see in modern cinema: it doesn't have a narrative plot -- not that I can follow, anyway -- but is instead a series of disorienting images calculated to create a mood in its audience, but not to tell a story.
To summarize the film would be pointless. All I can tell you is that it concerns a woman named Arletty who is looking for her estranged artist father. She falls in with a smooth, suave ladies' man named Thom who might be the devil or the antichrist or just a womanizer. Then a lot of very dark, very confusing stuff happens. Arletty coughs up a beetle, and discovers that she can no longer feel pain. Her father eventually turns up, and tells her the story of an otherworldly "dark stranger" who traveled with the Donner Party a century ago and vowed to return in a hundred years.
Does that sound like a movie you want to see? Probably not. But it is. My God, it is strange. It's like watching someone else's dream. I've only seen a few movies like this one, and it's difficult to find the right way to recommend it; on one hand, I don't want to scare you off. On the other hand, if I over-hype it, you won't enjoy it at all. I will say that this is territory frequented by David Lynch and (when he was feeling particularly unfriendly to his audience) Stanley Kubrick. Carnival of Souls is a similar film of similar vintage, but that one at least made some concessions to its audience. Messiah of Evil is a puzzle with no answer. It doesn't need one. To scrutinize this movie would miss the point; you have to surrender yourself to it.
Amazingly, it's the work of Willard Huyck and Gloria Katz, who would later write three films for George Lucas: American Grafitti, Indiana Jones and the Temple of Doom, and Howard the Duck. All three are unloved by me, though I appreciate the appeal of at least two of them. How the writers of Howard the Duck managed a film as intricate and effective as this is beyond me. I'd second-guess my own opinion if not for the fact that Messiah of Evil actually has a pretty serious cult following.
There's likely no one in this movie that you've heard of, but Marianna Hill carries Arletty rather nicely, and the aforementioned Royal Dano does a wonderful voiceover narration which I honestly didn't think he had in him (actually, I thought he sounded like Leonard Nimoy...). Elisha Cook, Jr. shows up as a wino, and if you watched as many old movies as I do, you'd recognize him as a staple of old horror movies. You've seen him: he's the one with wide, frightened eyes who always warns the main characters to turn back.
Also, I feel that I would be remiss in my duties as a kibitzer if I failed to mention that one of the womanizing antichrist's girlfriends is played by an actress named Joy Bang. That's her married name, not a stage name, but she's famous for exactly what you'd expect.
People point to this as a Lovecraftian film, and I'm not sure I agree with that. I think Uncle Howie would've approved of it, but I see none of his influence here, in spite of the fact that this film, like his stories, exists more for the atmosphere than for the narrative. If you pressed me for comparable stories by HPL, I'd recommend "The Outsider" and "The Night Ocean." "The Outsider" gets too much attention, considering that it's basically just HPL feeling sorry for himself in a very public fashion, and "The Night Ocean" was ostensibly written with his protégé Robert H. Barlow, though the general consensus is that Lovecraft had almost nothing to do with it. If you're still with me, skip "The Outsider" and read "The Night Ocean."
You can watch the trailer here, but I recommend that you just dedicate 90 minutes and watch the whole thing.