KIDNAPPED IN THE JUNGLE
A hint of buried treasure leads Hal deep into the Central American jungle.
THE COPPERHEAD TRAIL MYSTERY
What was the meaning of the baffling and blood curdling events that centered about the ranch where Hal Keen had gone in search of gold?
THE SMUGGLERS’ SECRET
Hal Keen sets out to get to the bottom of a mystery that threatens the safety of a whole community.
THE MYSTERIOUS ARAB
Mystery, excitement, murder in a scientist’s camp in the jungles of Africa.
THE LONESOME SWAMP MYSTERY
The lonely and mysterious swamp gave up its secret only after a series of terrifying events.