Arriving in Washington D.C. on the heels of the election of President John F. Kennedy, Kimberly Sayers finds work at the White House as boyfriend John Loengard plunges into his job as an aide to Congressman Charles Pratt. Sent to look into the Air force's investigation of UFO sightings, John meets a couple who claim to have been abducted by aliens. And back in Washington, he's accosted by the mysterious Navy Captain Frank Bach, whose history with UFO's dates back to when spy plane pilot Francis Gary Powers was downed over the Soviet Union while pursuing an alien spacecraft. Though warned that it's too risky, John confronts Bach and is recruited into the top secret Project Majestic, whose most closely guarded secrets include the body of an extra- terrestrial. With his girlfriend and his boss in the dark, John is sent to interview an Idaho farmer who has been inhabited by a parasitic alien life form that Bach says are taking over human bodies. Then, as Kim suspects John's comings and goi

Following the Kennedy assassination, Bach heads for Dallas to recover the artifact Loengard used to prove the alien invasion to the President. However, when he's sent by Robert Kennedy to get it too, John meets Jesse Marcel, a government official who was in New Mexico when President Truman learned firsthand of the invasion, and who claims that an alien craft long suspected to have crashed there was really shot down.

A dream is drawing Sayers to Florida. And though Bach isn't far behind, Loengard reluctantly agrees to help find the astronaut she's seeing. As Majestic prepares a space probe to locate the alien base, Kim and John arrive in Cape Canaveral where she spots Ty Yount, an astronaut who she thinks was with her on the alien ship. And while Yount admits he's been dreaming about her too, he's hustled away by crew mate Gary Augatreux - but not before slipping Kim a note requesting that they meet. Meanwhile, having survived his seemingly fatal encounter with the Loengard family in California, Majestic cloaker-turned alien Jim Steele continues his pursuit of John and Kim.

Tracing alien radio transmissions received in New York City, Loengard and Sayers suspect the Hive is planning an operation around the American debut of the Beatles on The Ed Sullivan Show. At the studio where preparations are underway, they find nothing suspicious. However, after learning the radio operator they're tracking died recently in a mysterious traffic accident, they find a second phone number for another suspect operator. Meanwhile, Bach stumbles onto evidence that the Hive has been rejecting some abductees.

With $500 in poker chips they found on Steele, Loengard and Sayers head for Las Vegas. As John makes his way to the gaming tables, Kim lands a job and meets Susan Swenson, a cocktail waitress who already knows more than she wants to about a scheme to use casino winnings to finance a Hive operation. Meanwhile, as John zeroes in on some big winners he suspects are using telepathy beat the odds, he and Kim are brought in to meet with the eccentric casino owner, Howard Hughes.