Laurie’s review published on Letterboxd:
Peter Weller plays a house-proud yuppie (Bart Hughes) battling a diabolical rat for possession of his swanky New York townhouse. Had it been made a few years later, George P. Cosmatos's rodent themed horror certainly would've been played for outright laughs. Instead, Of Unknown Origin resides in a tonal twilight zone that swings back and forth from genuinely unsettling to absurdly ridiculous. Not that this battle between bank executive and rat doesn't induce an intended giggle here and there, it's just that the decline of Bart's performance at work (really anxiety inducing!) and the literal destruction of his home are effectively played to feel like super-high stakes.
The film's greatest strength is the fact that the rat isn't some monster-sized mutant killing machine. Admittedly, the 'visitor' is on the big side and exhibits a devious level of intelligence (destroying the cheque left for the rat catcher!), but what distinguishes this rodent nemesis from its cinematic horror kin is that it's nothing more than one bastard rat in a city teeming with them. That said, it would make a great double bill with the giant steroid pumped mutant rat horror Deadly Eyes, which is also set in scuzzy early 80's New York.