An urgent call for help from their father's friend, chemist Sam Gentle, has drawn Frank and Joe across the country to northern Arizona. The cryptic message offers no clue to the danger he's in, and it's one secret he will never reveal. For when the Hardys arrive, they discover Sam's been the victim of murder. . . .
- ISBN10 0606058621
- ISBN13 9780606058629
- Publish Date 31 December 1993 (first published 1 November 1993)
- Publish Status Unknown
- Publish Country US
- Imprint Demco Media Inc
- Format Hardcover
- Pages 153
- Language English