Maybe I would have been lost anyway, but it's worth noting a great deal of The Visitor suddenly made sense in the end. Whether or not the rest of it means anything is up to the individual viewer.
You'll probably want The Visitor to take you on a cosmic trip. With exposition like Nero's, though, the film is like winning a free vacation, but only after listening to a sales pitch for timeshares. I'm not saying it's a bad movie. It's actually quite good for borrowing so heavily from so many different sources. (Rosemary's Baby and The Omen came to mind for me. Others have compared it to everything from The Exorcist to Star Wars.) Despite these obvious influences, you've never seen anything like The Visitor and you'll never see anything like it again.
Following its dreamlike prologue, the audience is whisked away to the un-magical land of a basketball game in Atlanta, Georgia. When the away team nearly turns over the score in the final seconds, a little girl in the front row uses her supernatural powers to make the basketball explode in the player's hands. (No one seems to think it's weird that the basketball blew up like a gunpowder-stuffed piñata. You'd think any ref who witnesses something like that would at least call interference.)
The eight year old girl responsible for the exploding basketball trick is accompanied by her mother, played by Joanne Nail (Switchblade Sisters). Nail's character is being courted by Lance Henriksen, the owner of the basketball team. Henriksen proposes to the girl's mother, who refuses his offer despite creepy persistence. We soon learn Henriksen is an agent of evil when we see him in the boardroom of rich and powerful Illuminati types. The mysterious figures, led by Mel Ferrer, remind Henriksen that their evil plot hinges on Nail getting pregnant again. Apparently their goal is the sort of event that happens whenever the gatekeeper comes into contact with the key master.
Meanwhile John Huston's character, the inter-dimensional traveler from Nero's plane of existence, arrives on Earth. He can freely hop between realms, but requires a commercial airliner to take him to Atlanta. When the little girl discovers her arch-nemesis is on Earth, she angrily uses her Omen-like powers to turn a birthday gift into a loaded gun and promptly shoots her mother in the spine. This "accident" leads to a couple more surprisingly high-profile talents: Shelly Winters and Glenn Ford, who play the new nanny and a police detective. Later the film will introduce Nail's ex-husband, a doctor played by Sam Peckinpah.
Seriously. All these people are in this movie. If you only like one of these people, you owe it to yourself to see this movie.
The problem with The Visitor (and I'm nitpicking here because the more I look back on it, the more I like it) is it has too much plot for what it wants to be. And it's a plot that will be just a little too familiar for fans of pre-Halloween horror. I usually love movies like this and I'm no stranger to psychedelic journeys, but no one's asking directors of acid films to stitch together their visual exercises with coherent—but ultimately pointless—plots. I just feel The Visitor would work a lot better if it didn't try to be so damned routine in between its short bursts of wonderful lunacy.
The Visitor is a film for viewers who love film itself. I couldn't recommend it to anyone else.