The Harts south-of-the-border boating holiday turns Jonathan and Jennifer into desperate fugitives, on the run from Mexican police and a gang of drug dealers.

A young boy shows up at the Harts gate in the middle of the night claiming to be Jonathan Hart, Jr. The child proves to be the unwitting pawn in his biological father's criminal plot.

The Harts become involved in the world of espionage when Jonathan purchases an antique car for Jennifer. A mysterious jet-setting couple will stop at nothing to acquire the classic auto.

A deranged woman who works for Hart Industries has an obsession for Jonathan. She sees Jennifer as a threat to her fantasies of love and finds it essential to eliminate her.

When a prominent lawyer is murdered, two close friends of the Harts are accused. Jennifer sets out to clear the wife while Jonathan attempts to absolve the husband.

An article written by Jennifer leads a prostitute to ask for her help and the Harts go under cover to bait a killer who is murdering prostitutes.

A Hart Industries chemist is shot and the Harts suspect a female scientist who has discovered a powerful new narcotic. Jennifer and Jonathan find themselves in a weather chamber subjected to brutal and swift changes in temperatures.

The Harts are invited to the wedding of Jonathan's former girlfriend in Monte Carlo. She is being forced into a marriage to a power-hungry, ruthless, blackmailer. The Harts uncover the truth and help foil the wedding plans allowing Nikki to marry the man she really loves.

A dying man gives Jonathan and Jennifer an ancient Buddha statue. The Harts are then thrown into intrigue and danger when they are pursued by Chinese henchmen and a diabolic giant.

Jennifer has her protrait done as a gift to Jonathan for their anniversary. When the young artist is murder, the Harts mingle in the high-society art world where Jennifer becomes the target of a shady art speculator.

The Harts suspect a college fencing champion of being behind a murderous drug ring. Jonathan fights a razor-sharp duel with the sadistic student.

The Harts are invited to a unique, off-beat party -- a treasure hunt at a haunted house. When another guest is murdered, the Harts race against time to find the murderer before someone else becomes victim.

Freeway runs away with a gun used to murder a wealthy neighbor. The Harts get involved in capturing the killer and intercepting a multi-million dollar jewelery shipment.

Intrigue in Vail lead Jonathan and Jennifer into the midst of severe bizarre murder plot, including an electrifying scheme against them.

The Harts are asked to ransom two scientist employed by Hart Industries when they are kidnapped in South America. When Jonathan, Jennifer, and Max, they wind up mounting a mid-night raid against the wealthy and powerful kidnapper.

The Harts have a deadly encounter when they enter the mysterious world of psychic phenomena. A Hart Industies employee with amazing powers of ESP, a twin sister, and a wealthy grandfather, becomes the target of a deranged killer.

The Harts uncover a scheme designed to blackmail wealthy patrons of a beauty salon.

The Harts take a luxurious cruise on a Hart Industries liner to investigate a series of jewel thefts. They find themselves at the mercy of the jewel thieves' rival burglars.

The menu features murder when the Harts take a gourmet cooking class. The Harts vie with an unscrupulous financier for a recipe which might benefit the world.

The Harts are caught up in a tangled scheme when a wealthy playboy attempts to take over the family fortune using his brother's wife as his unknowing pawn.

When a bridegroom disappears abruptly and leaves his wife, who is an acquaintance of Jennifer's, to face a couple of thugs by herself, the Harts step in to help her.

Jonathan witnesses a murder. In his rush to approach the scene of the crime, he is hit by someone on a mo-ped. The blow to his head causes temporary amnesia and the killer must get rid of Jonathan before his memory returns.

Jennifer is mistaken for her look-alike, Dominique, and is kidnapped by ruthless killers. With the help of an unscrupulous columnist, the police, and the real Dominique, Jonathan devises his plan to save Jennifer.

Normally finicky, Freeway is quite fond of a new dog food and ends up in a dog food commercial. When the Harts have a party, some of Freeway's new food is mistakenly ingested by some guests who then behave as if drugged. Jennifer and Jonathan are in danger when they attempt to find out its secret formula.

Industrial espionage is a problem at Hartoy company. When the investigator Jonathan has hired is murdered, the Harts go undercover in an attempt to foil the crooks and save the company from financial destruction.