Hardy Boys 13 The Mark On The Door

In their motorboat the Sleuth Frank and Joe Hardy search Barmet Bay for a dangerous stranger who has stolen a valuable boat. Suddenly, in the eerie fog, they spot the craft drifting aimlessly out to sea. What happens next starts the young detectives and their pal Chet Morton on an intriguing adventure that takes them to Mexico and into the comparatively unexplored desert and mountain regions of Baja California.

The search for a stolen boat leads the Hardy brothers to Mexico where they become involved with a band of Indians and a strange smuggling operation.

The search for a stolen boat leads the boys to Mexico where they encounter a strange smuggling operation.

Frank and Joe Hardy become involved in an intriguing mystery which revolves around their fencing master, Ettore Russo. Proof that Russo is the rightful heir to his grandfather’s estate hinges on retrieving the guard end of a broken saber lost many years ago in California. The young investigators’ quest is complicated by a bank robbery during which some of their father’s important records are stolen. A chase ensues in the grape-growing region of California as the boys engage in a dangerous game of hide-and-seek with the bank robbery gang.

One exciting event follows another when Frank and Joe Hardy are hired to apprehend the pickpockets who have been plaguing Solo’s Super Carnival. When their friends Tony Prito and Biff Hooper exhibit a stuffed whale dug up at a construction project, they all but put the carnival out of business. In this thrilling mystery the young detectives pit their wits against a gang of thieves whose bizarre identification, a three-part whale tattoo, proves to be a nearly insolvable riddle.

Rarely do magicians reveal their professional secrets. Consequently Frank and Joe Hardy are amazed when a well-known magician, the Incredible Hexton, offers to reveal the secret of his “Vanishing Man Act” and invited Mr. Hardy to be the subject. When their detective father fails to reappear, his sons are convinced that something sinister is afoot, despite Hexton’s insistence that Mr. Hardy is playing a joke on them. While desperately searching for their father, Frank and Joe find themselves working with SKOOL, a U.S. organization of secret agents pitted against UGLI, an international ring of spies stealing government secrets domestically and internationally. The young detective’s gripping adventures culminate in a dramatic climax when they unmask the secret agent on Flight 101.

The Hardys purchase a Chinese junk to use as a ferry service, in order to make some money over the summer. It soon becomes apparent that others are very interested in the ship.