Some sources refer to Keel's book as a work of nonfiction, which would appear to be the same as labeling The X-Files a news program. In brief, the "facts" around the Mothman phenomenon are these: From the summer of 1966 to late 1967, various residents around Point Pleasant, West Virginia, claimed to have seen a humanoid creature, about seven feet tall, with red eyes and large wings. He would often contact people while they were in their cars or by looking through the windows of their homes. An editor at the Associated Press came up with the name Mothman, the catchiness of which assured further publicity for the alleged creature.
While Mothman's voice was described as a high-pitched squeal, he also supposedly issued warnings about upcoming catastrophes, not all of which panned out. In December 1967, the area was struck by a real catastrophe -- relating the details would spoil the film's ending -- and Mothman either disappeared or greatly curtailed his public appearances afterward. It might be churlish to point out the synchronicity of these events with the rapidly spreading availability of marijuana and various lysergic acid formulations in the outback during that period -- in other words, to suggest that Mothman wasn't the only one with red eyes.
Director Mark Pellington and screenwriter Richard Hatem essentially use Keel's book as little more than a jumping-off point for a feature-length X-Files or Twilight Zone episode. In their version, Klein's involvement starts two years before Mothman first shows up, when Mothman has some never-exactly-defined involvement with the death of Klein's wife (Debra Messing).
Then, one night, while he's driving to an interview with a presidential hopeful, his car breaks down near Point Pleasant, and strange things begin to happen to him. With the help of comely town cop Connie Parker (Laura Linney), he interviews locals who have suffered through similar weird encounters. He jets off to Chicago to interview Alexander Leek (Alan Bates), a professor whose career was ruined by his own experiences with Mothman (or some facsimile). Things escalate, and it increasingly seems there is some big pattern, some purpose linking the death of Klein's wife and Mothman's warnings and Connie's dreams. You begin to wonder when the hell Scully and Mulder are going to show up.
The Mothman Prophecies may be stupid, but it's also effective in many ways. Pellington appears to have studied Twin Peaks -- a fine place to start for this sort of material -- and his visual style is genuinely creepy. Likewise, Gere is a wise casting choice: He manages to convey utmost sincerity without making himself look like an idiot.