4 X Hardy Boy Adventures by Franklin W. Dixon Paperback Books - Mystery Of Phantom Heart, Into The Thin Air, The Battle Of Bayport. This set from the Hardy Boys Adventures series offers young readers thrilling action, adventure, and crime-solving mysteries. Published by Simon & Schuster in 2014, these novels are perfect for young adults and ages 9-12. With large print and unabridged content, these books provide an engaging reading experience for fans of the genre. Get ready to embark on exciting adventures with the Hardy Boys in this captivating collection.