The Infinity Clue
Ghostwriter Karl Harr III[1]
Illustrator Leslie Morrill (1981)
Cover artist Steven Assel
Publication information
Publisher Wanderer Books
Producer Stratemeyer Syndicate
Publication date 1981
Media type Paperback
Pages 190
ISBN ISBN 0-671-42343-6 (paperback)
Series The Hardy Boys
Preceded by The Four-headed Dragon
Followed by Track of the Zombie


The Infinity Clue is the 70th book in The Hardy Boys. It was first published in 1981 by Wanderer Books (an imprint of Simon & Schuster).

Plot summary

From back cover:[2] A mysterious telegram is sent to Frank and Joe from Mr. Hardy, who is working on a case in Europe. The cryptic message tells the boys to go to Washington, D.C., and it warns them to watch out for "infinity!"

Despite an anonymous threat on their lives, they head for the nation's capital, but are plagued by strange accidents. They follow a clue that leads them to a geological site on East Coast, and strange things begin to happen. No light is shed on the mystery until they find a kidnapped girl on a deserted island, and they realize that not only they, but thousands of people are in danger!


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Businesses and organizations



  1. Who Wrote the Hardy Boys? at
  2. The Hardy Boys #70 The Infinity Clue first printing back cover

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