Man vs. beast, a perennial narrative for as long as there have been narratives. Rich, fertile ground for storytellers. Combine that with the creepy-crawly subgenre of horror, and you get Of Unknown Origin. Directed by George P. Cosmatos way back in 1983, Of Unknown Origin tells the tale of Bart Hughes (Peter Weller), an investment banker of some sort, and the confrontation he has with a rat.
Peter Weller does a fine job with Bart. Weller is an intelligent and erudite man in real life, so it’s little surprise he can pull off a youngish man on an ascent up the corporate ladder. He’s a smooth character, with enough of the wiseass about him to make his behavior in the film believable.
Bart’s life seems to be going well. He has a hot wife (Shannon Tweed) and an adorable son, the three of them living in a large house Bart remodeled himself. He’s in line for a big promotion at work, and although the job has its fair amount of stress, Bart is handling it. It’s at home when things begin to go awry.
After his wife and son leave town for a spa trip, Bart begins to notice some things going wrong with the house. After a drain pipe on the dishwasher floods the kitchen, Bart learns that he has a rodent, probably a rat. On the advice of the super from the apartment building next door, Clete (Louis Del Grande), Bart sets out traps rather than call an exterminator. Clete is an interesting fellow. He has a whole mythology regarding city rats built up in his head, painting them in almost epic 
proportions. Rats are not to be trifled with. They are the equal of man, and it would be a mistake to underestimate them. When a rat invades a person’s home, the man may spend 20% of his time thinking about the rat, but the rat is spending all its time thinking about the man. Del Grande does a fine job portraying Clete as a guy who has probably spent too much time in his basement. At least his head didn’t explode in this film.
If the rat isn’t menacing enough for a viewer by this point, Cosmatos and crew begin to ratchet up the visuals, offering quick glimpses of the rat here and there, growing in frequency throughout, and it’s a nasty creature. Its fur is matted, soaked in dank water or slime. It leaves a disgusting trail wherever it waddles. Its mouth is a blend of spit, grime and blood, always shown in closeups for effect. Rats aren’t as gross in real life as they are in this movie. That’s an accomplishment, considering the amount of subway rats I’ve seen skitter past in the night. They truly are foul creatures, comfortable in the dark, among filth, their own and from other sources. They eat their young. They spread disease...I imagine that if rats weren’t so thoroughly skilled at making people squirm, there would be more than just a handful of movies made about them. But they create such a visceral disgust that it’s just too much to ask audiences to bear on a regular basis.
Of Unknown Origin tries to walk a fine line figuring out just how much rat is enough. If you hate, hate, hate rats, Of Unknown Origin walks the wrong side of that line. If they just creep you out, the film is very good at sending chills up and down a viewer’s spine.
As the film goes on, the rat begins to turn poor Bart’s life upside down. He’s neglecting his work, taking long lunch breaks to research rats in the library, coming in late and leaving early. At a dinner party, he regales the other guests by going into statistical detail about the menace that is genus Rattus. Back at his home, his wife and child still mercifully away, the rat is chewing Bart out of house and home. As the damage becomes more extreme, so do Bart’s methods, until an incident in the boiler room makes it personal. From this point on, it’s a war between Bart and the rat. The movie makes it clear only one of them will survive. Will it be the possum-sized rat with an oversized aggression to match, or will it be the unhinged white-collar yuppie who will be damned if some rodent is going to drive him out of his house? Cosmatos didn’t telegraph the answer at all. Right up until the end, a viewer has no idea how things will turn out.
This movie bombed when it came out, and critics hated it. As for myself, I was creeped out, and satisfied. The acting was good all around, it had some good scares despite the occasional high levels of cheese, and it was tense. It’s not a top-tier horror fest or psychological mind-fuck, but films like that are few and far between. What Of Unknown Origin is, is a small film that breaks its constraints thanks to a talented cast, and a director who played above his normal game.