Park, one of the infected crewmen from the Big Horn, kills a detective at a Baltimore port during a shoot-out with an Asian gang that is smuggling highly sophisticated computer microchips. When Molly arrives on the scene, she learns that Park survived being shot at the docks and electrocuted on a nearby fence while he was trying to escape. But what she learns next worries her the most: human technology can create the deadly alien signal.

While a security leak threatens to put the Threshold plan in jeopardy, Molly fears that residents in a small Rhode Island town may have been infected by the alien signal after several people reported having disturbing dreams about trees made of glass. The leak is brought to Molly's attention when a newspaper article appears that vaguely mentions Threshold. Unfortunately, the article gets a meddling senator's attention and he insists on being included in the project.