- "The future is in the stars...the possibilities unlimited...the dangers beyond belief!"
- — Tag-line, from front cover
The Alien Factor is the second and last book in Hardy Boys and Tom Swift Ultra Thriller series. It was first published by Archway Paperbacks (an imprint of Simon & Schuster) in June of 1993. Produced by Byron Preis Visual Publications, Inc.
- Back cover summary:
A Deep Secret From Deep Space Puts Frank and Joe and Tom Into The Deepest Trouble Imaginable...
Tom Swift has caught a falling star---a visitor from outer space who is as beautiful as she is strange. But his secret encounter has set off alarms at the highest levels of government. A top-secret intelligence agency believes he's involved in an espionage and smuggling ring. To check Tom out, the Network sends two of its top operatives: Frank and Joe Hardy.
But when the alien is kidnapped by a sinister industrialist, Frank and Joe and Tom realize that they have to work together. They're dealing with a conspiracy that stretches from the farthest reaches of space into the deepest recesses of their own government. The fate of the country and the planet could rest on uncovering the shocking truth about the girl from another world!
- Harlan Ames
- Rick Cantwell
- Dan Coster
- Mandy Coster
- The Gray Man
- Frank Hardy
- Joe Hardy
- Mina (aka M'na)
- Rob the Robot
- Mr. Sunshine (aka Eric Laidlaw)
- Mr. Swift
- Tom Swift
- Burger Master parking lot
- Central Hills
- Nevada Desert (location of Eric Laidlaw's home, Solitude)
- San Diego
Businesses and organizations
- T'wikt'l (species)
- Because the timeline was reset at the end of A Hardy Boys and Tom Swift Ultra Thriller: Time Bomb, Frank, Joe and Tom have no memory of the events that happened in that book, except for what occurred in the last chapter when Fenton Hardy and boys went to see Mr. Swift and Tom about a shoe print that had been found near some dinosaur tracks.
- Joe has a cold at the beginning of this book.
The following books were referenced to in the text of The Alien Factor: