Franklin W Dixon

Frank and Joe get mixed up in mystery with the help of a short-wave radio.

Every night water strangely disappears from the new reservoir near Skull Mountain. Frank and Joe join forces with a team of skilled engineers to solve the baffling mystery.

In England to discover the secret of the Silver Knight in Bromley Hall, Carson Drew and his daughter Nancy encounter Frank and Joe Hardy in their hotel and the four proceed to unravel the mystery. The reader's choices determine the direction of the investigation.