The famous young detectives Frank and Joe Hardy are caught up in a dangerous web of intrigue when they agree to help Greg Woodson search for his grandfather’s missing will. When Henry Kurt, the temporary headmaster of Woodson Academy, insists that he is to inherit the property from Greg’s grandfather, the case becomes even trickier. Frank and Joe must risk their lives several times before they solve the mystery of Yellow Feather and trap a sinister criminal who will stop at nothing--even murder--to satisfy his greed for money.

When the Hardy Boys eagerly agree to assist their friend Jack Dodd and his father in locating a family treasure, the two young detectives are unaware of the baffling complications that will arise. Deadly road traps, aerial ambush, a spider man and a suspect who carries a menacing cane harass the young detectives as they seek the triple solution to this perplexing and exciting mystery.

Private investigator Fenton Hardy enlists the aid of his teenage detective sons in a search for a missing man being sought by an insurance company. All leads to the sailor’s whereabouts have petered out and the boys fly to Iceland, the man’s native land, hoping to find a new clue. From the moment Frank and Joe arrive in Reykjavik, the capital city of Iceland, they are in constant danger. In the spine-chilling pursuit that follows, Frank and Joe uncover a diabolical espionage plot that threatens the life of a U.S. astronaut and NASA’S moon project.

When Frank and Joe Hardy receive a telegram from Tony Prito in Alaska telling them that his life is in jeopardy, they immediately make plans to fly to Tony’s rescue. Unknown enemies dog the Hardys and their pal Chet Morton even before they start the 4,000 mile journey. Puzzling questions lead the Hardys into dangerous sleuthing in the wilderness of Alaska and British Columbia. The astounding secret that the young detectives uncover, in the shadow of the forbidding mountain peak Devil’s Paw, winds up one of the most perilous adventures they have ever encountered.

Caught in their motorboat the Sleuth by a sudden storm at sea, Frank and Joe Hardy are relieved to see the lights of a yacht. But their SOS ignored. The shrill sound of a siren fills the night air and moments later a helicopter drops an object alongside the Sleuth: a wallet containing two thousand dollars! The next day, a truck carrying a shipment of high-powered rifles has been stolen. These two apparently unconnected events are clues in a tangle of mystery which turns out to be one of the detective brothers’ most exciting adventures.

The young detectives receive a trained peregrine falcon as a gift that involves them in an exciting mystery. Imagine their astonishment when the swift-flying falcon brings down a homing pigeon carrying two precious rubies! Startling events that ensue indicate the gems are a ransom that has been paid for the release of a kidnapped student from India, who had come to the United States to complete his education. But Tava, the son of a wealthy industrialist, is still being held captive. Hoping to find a clue to Tava’s whereabouts, the Hardys try to track down the owner of the ruby-bearing pigeon. Their every move, however, is thwarted by the dangerous criminals not only involved in the kidnapping, but also in the large-scale smuggling of aliens from India to the United States. How Frank and Joe eventually outwit their adversaries climaxes this thrill-packed mystery adventure.