Threshold

Molly and Cavannaugh travel to the town of Allenville to investigate a scientist whom they believe is actually one of the aliens. They discover a beacon he's constructed, designed to guide another alien probe to Earth, this time right over Washington, D.C. Meanwhile, Nigel, Lucas and Ramsey deal with the infected mother when they realize that she is trying to poison her baby; and, once Allenville is contained, Molly receives a message through a dream telling her that the humans will eventually prevail and Earth will be saved, but that she will pay the ultimate price in saving it. less

With food supplies now infected with the alien DNA, the team tries to find the source of contamination before the outbreak becomes a population. Meanwhile, Lucas has an encounter with a Civil War-era human who somehow defeated the aliens back in the 1800's, and the only clue to how he accomplished this can be found in his journal. But Lucas doesn't know where to find it; and, Molly meets with an alien, who tells her that they have come to save human beings, as radiation from two collided neutron stars approaches Earth and will kill all life on it, unless human physiology is altered. less

Molly and Baylock decide to move the infected prisoners, who have just attempted to escape. During transport, a commando unit led by a discharged soldier manages to free one of the prisoners. Meanwhile, Lucas' behavior becomes erratic, and the team quickly discovers that his lengthy exposure to the signal is the cause. less