While taking in the sights of Paris in 1979, the Doctor and Romana sense that someone is tampering with time. Who is the mysterious Count Scarlioni? Why does he seem to have counterparts scattered through time? And just how many copies of the Mona Lisa did Leonardo da Vinci paint?

Searching for the third segment to the Key to Time brings the Doctor and Romana to present-day Earth, where the travellers have to contend with stone circles, Druidic rituals and a not-so-mythical goddess known as the Cailleach.

The Doctor and Romana follow a distress signal which leads to the jungle planet Chloris, whose ruthless ruler Lady Adrasta harbors a deadly creature in a pit.

Finding the fourth segment of the Key to Time was simple enough, but holding onto it may be another matter. The Doctor and Romana find themselves embroiled in the political games of the planet Tara, where doubles, android or otherwise, complicate the coronation of Prince Reynart.

Romana fancies a proper holiday and convinces the Doctor to visit the leisure planet Argolis, where a takeover by the Argolins' historic enemy is underway.

Unstable security chief of an auction house becomes increasingly obsessed with his female neighbor, who's being stalked, and a supposedly cursed jewel that's being auctioned. Is he losing his mind or is the curse real?

A scrying glass puts an antiques exporter in the path of a woman fleeing from devil worshipers and the evil hypnotist who leads them. Originally an episode of British horror anthology TV series, Hammer House of Horror, that later received a feature release in the United States.