The Hardy Boys: Undercover Brothers
The Hardy Boys: Undercover Brothers is a detective fiction series of books, which replaced The Hardy Boys Digest paperbacks in early 2005. All the books in the series have been written under the pen name of Franklin W. Dixon.
| Links | https://en.wikipedia.org/wiki/Undercover_Brothers |
Series 4
 | Extreme Danger | Paperback |
 | The Children of the Lost | Paperback |
 | Lost Brother | Paperback |
 | Forever Lost | Paperback |