The robbery of the treasure in the tower proves to be an exciting challenge to Frank and Joe. Frank and Joe attempt to foil a ruthless espionage ring in their effort to sabotage the United States space program.

The essential facts of ten mysteries are presented, giving the reader the opportunity to solve the cases before examining the boy detective's solutions.

Nancy receives a letter meant for a British heiress who has the same name and, in her attempts to contact the other young woman, faces danger from a man who operates a Lonely Hearts Club mail fraud.

"When Kade Logan said goodbye to his estranged wife eight years ago, he never thought it would be the last time he saw her alive. Now her car has been hauled out of a nearby lake and Kade is determined to track down the man who murdered her. Enter Eleanor Bowman, a talented private investigator who's about to stir up a hornet's nest on his Colorado ranch. With old scandals still buzzing about his late wife's many affairs and new violence erupting,...

A brass-bound trunk mistakenly delivered to Nancy's cabin on a New York-bound ocean liner becomes the first clue leading her to suspect that international jewel thieves are aboard.

In solving the mystery of two medallions missing from an inherited curio collection, the Hardys wind up in a desolate area of Guatemala at the mercy of dangerous thugs.

When ten people arrive on private Indian Island off England's southwest coast, lured to a mansion by invitations from a mysterious host, terror mounts as one guest after another is murdered, in a classic whodunit that is an elaboration of the famous children's rhyme "Ten Little Indians."

Nancy Drew must use clues in a dead man's letters to find some unpublished musical manuscripts that will save an old man and his granddaughter from financial ruin.