Ironhorse and his team of special forces are thwarted when they attempt to ambush a trio of alien truckers. Meanwhile, Harrison, Suzanne and Norton consult with noted linguist Adrian Bouchard - a specialist in unusual languages, he has apparently cracked the alien code after intercepting a series of radio transmissions.
Weighing their options, the trio shares confidential information about the alien invasion with Adrian, who begins working with Norton to analyze a new series of transmissions. But when Adrian's computer overloads, the team is forced to break security and use the super-computer back at headquarters.
With Adrian's know-how and the sophisticated technology, Norton and Adrian are able to miraculously break the alien code on the first try. With this sudden burst of success, the team learns that the aliens are planning to converge on an area near headquarters.
However, disurbing things are occuring - and they revolve around Adrian. For example, Debi's new dog takes an instant dislike to him and abruptly disappears. Moreover, Adrian's apparent euphoria at breaking the code seems hollow and he appears to have an abnormal appetite for vegetables. Unbeknownst to the team, there is an alien in their midst.
Rushing to the site of the supposed alien operation three hours in advance, Ironhorse, Harrison and Suzanne are shocked to find the aliens laying a trap for them. Suddenly, the trio adds up all the inconsistencies in Adrian's behavior and race back to headquarters, hoping it's not too late.
But it is. After groundskeeper Tom Kensington discovers the mutilated body of Debi's missing dog, Norton figures out that Adrian duped the team so that he could secretly download all their secret files to give to the Advocacy. When Norton confronts Adrian, the alien mercilessy murders Kensington when he tries to defend an unarmed Norton. Luckily Norton is able to kill Adrian before he harms anyone else.
Arriving back at headquarters, Ironhorse, Harrison and Suzanne are saddened to learn that Kensington has become the team's first casualty in their war against the aliens.