A Hardy Boys and Tom Swift Ultra Thriller

The Ultra Thriller series is a crossover series produced by Byron Preiss Visual Publications, Inc. between August 1992 and June 1993. The series was published by Archway Paperbacks, an imprint of Simon & Schuster Inc.. It was a spin-off of the current Tom Swift (Archway) series and The Hardy Boys Casefiles. While the series had the Hardy Boys billed as the top stars, Tom Swift was the real star of the series.

List of titles

 * Time Bomb (August 1992)
 * The Alien Factor (June 1993)