After Joe Hardy's fiancée is killed by a hit-and-run driver, the FBI won't let the police arrest the man until their own case against him is finished. Joe takes the law into his own hands and goes undercover as a rich gambler with underworld connections.
Guest Stars:
Kevin Brophy, Anne Lockhart, Mills Watson, Kevin Tighe, Jack Kelly
Joe Hardy is still haunted by memories of his dead fiancee, but has to focus his mind on the case when Jocco's girlfriend overhears him talking to the police on the phone. Meanwhile, Frank Hardy tries to help Joe by going undercover too, but Jocco finds out and traps Frank in a shark-infested area.
Guest Stars:
Kevin Brophy, Anne Lockhart, Mills Watson, Kevin Tighe, Jack Kelly
Joe and Frank Hardy go to London to find their missing father, but when Frank goes missing as well, Joe and an agent from the British Ministry must find a traitor together.
Guest Stars:
Leon Ames, Dana Andrews, Pernell Roberts, Patrick Macnee, Ian Abercrombie
In Greece to investigate drug smuggling, the Hardy Boys pose as archeology students on a dig for the lost city of Atlantis, but they are dogged by suspicious accidents and a dead body.
Guest Stars:
Lloyd Nolan, Darleen Carr, Gino Conforti, John Colicos, Jack Kelly
Frank and Joe Hardy journey from the South of France to the Caribbean to find a girl who disappeared while hunting for pirate treasure.
Guest Stars:
June Lockhart, Dane Clark, Robert Loggia, Frank Marth, Jack Kelly
Frank and Joe Hardy are assigned to go to Puerto Rico to protect a senator's daughter from an international blackmailer known as the Scorpion.
Guest Stars:
Macdonald Carey, Robin Mattson, Don Diamond, Joseph Ruskin, Jack Kelly
When the daughter of a Russian official defects to the U.S. by hiding in one of the rock band Bread's speaker cabinets sent to Hawaii, the Hardy Boys must track her down before the KGB does.
Guest Stars:
David Gates, Bobby Van, Jack Kelly, Doug Heyes, Jr., Nehemiah Persoff
Marla falls for an American agent, but Soviet killers pursue her.
Guest Stars:
David Gates, Bobby Van, Lloyd Kino, Jack Kelly, Nehemiah Persoff
A woman executes a securities scam from Atlantic City casinos using a code that the Hardy Boys must break.
Guest Stars:
Mary Louise Weller, Jack Kelly, Ed Gilbert, Nancy Morgan, Jim Raymond
Joe and Frank are assigned to protect a motocross racer, the daughter of a mob informant who has been threatened by assassins, but a strange woman has become obsessed with Frank.
Guest Stars:
Adam Roarke, Leonard Stone, Ana Alicia, Karen Lamm, Paul Coufos