John Klein (RICHARD GERE) is a respected reporter for the Washington Post who's just bought a house with his lovely wife, Mary (DEBRA MESSING). On their way home, however, she suddenly spots a large creature flying at the windshield, swerves out of the way and crashes their car. Severely wounded, Mary dies a few days later in the hospital, but not before sketching images of what looks like a humanoid figure with wings, a sight she worried that John didn't see.
Two years later, John is on his way to Richmond, VA to interview the Governor when he unknowingly ends up far away in the small town of Point Pleasant, WVA along the Ohio River. When his car suddenly stops working, he sets out for help and ends up on the doorstep of Gordon Smallwood (WILL PATTON), a resident who greets him with a gun.
Gordon reports to local cop Connie Parker (LAURA LINNEY) that this is the third time in a row that John has shown up in the middle of the night asking for help, an allegation the reporter denies and can't believe. No charges are filed as Connie reports that everyone in town has been acting weird recently, including those who've reported spotting a large, humanoid like figure with wings and glowing red eyes.
That revelation obviously sparks John's interest, and he thus begins investigating the matter, interviewing various eyewitnesses to the phenomenon and those who've been experiencing bizarre premonitions. After several of Gordon's dreams of impending disaster turn out to be true and John begins receiving bizarre telephone calls from someone or something that seems to know everything about him and what he's doing, the reporter sets out for Chicago to find Alexander Leek (ALAN BATES), an author of works related to paranormal events.
Although Leek is initially reluctant to speak with John, he eventually recounts tales of the Mothman, a mysterious, supernatural figure seen throughout the ages before various disasters have occurred. He warns John that such sightings mean something bad is going to happen in Point Pleasant. Yet, the reporter returns anyway, intrigued both by the mystery of it all and various ambiguous comments made about Mary, hoping to solve the mystery before disaster strikes again.