__WIKIA_BANNER__ The Hypersonic Secret is the 135th book in The Hardy Boys series. It was first published in December 1995 by Minstrel Books (an imprint of Simon & Schuster).
__WIKIA_BANNER__ The Hypersonic Secret is the 135th book in The Hardy Boys series. It was first published in December 1995 by Minstrel Books (an imprint of Simon & Schuster).