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.

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 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.

Jonathan and Jennifer's delightful excursion to the Scottish Highland games is laced with danger when Jennifer becomes the target of a man who is her rival for leadership of a world-famous clan.

Jennifer and Jennifer are stalked by dangerous industrial spies after they are entrusted with a dog that happens to be carrying a valuable biogenetic formula.

Jonathan and Jennifer pose as a professor and a student in a dangerous scheme to expose the person responsible for the drug framing of Max's nephew, a college basketball star.

The Harts and Max fear for their lives when the debt-ridden brother of Max's penpal believes Max is rich and comes to steal some of his fortune.