Helping in a case their father is working on, the Hardy brothers try to find an informer who has telephoned from a booth in their home town, and are hired by a carnival owner to spot pickpockets.

The Hardy boys' investigation of a museum robbery in England arouses the anger of a coven of black witches. There is no time for explanations when Mr. Hardy telephones Frank and Joe from the West Coast and sends them flying off to England to help his old friend Professor Rowbotham. Their stay in East Anglia begins with a weird omen, as they witness the bizarre funeral of an old witchmaster. From then on, strange things happen. They are shadowed,...

The Hardy boys go to Paris with a soccer team and investigate when the team's stadium and the entire city are under attack from an unknown enemy.

Frank and Joe pursue the robbers only to find out that they were tricked and they are in grave danger.

The Hardy boys investigate when someone tries to prevent a castle in southern France from being converted into a shelter for refugee children.

Frank and Joe Hardy are marked for death when they stumble upon an explosive secret hidden in the waters off the Caribbean island of St. Lucia.

While Frank and Joe Hardy join a team of storm chasers in Oklahoma, they encounter a bizarre phenomenon--the aftermath of a fierce tornado that defies scientific explanation.

Frank and Joe fight for their lives when they find the plane carrying a man who has connections to vital national security information has been sabotaged.

Visiting the site of Arizona's organ pipe cactus, Frank and Joe are astonished when someone begins stealing the rare cacti and selling them on the black market, and the boys prepare for a desert showdown.