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.

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 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.

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.

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.

Chief accountant of Hart Industries, Stanley Friesen, is set up to take a murder wrap after an evening on the town. In an attempt to clear him, the Harts retrace his steps and discover a gambling ring using the Nightlife as a cover.

An employee delivers some papers to Jonathan, along with evidence of a murder. She hides the clue in Freeway's toy and the Harts are held hostage by the murderer.

The Harts' unscrupulous lawyer hires an assassin to eliminate Jonathan with plans to court and marry Jennifer and thus gain control of the sizeable estate.