Residing on the threshold of E-Space with the Tharil Laszlo, Romana is on the trail of a terrible enemy. Allies of the enslaved, the duo ride the Time Winds in search of the desperate Sluagh. Meanwhile, on a bloody American Civil War battlefield, young soldier Joshua is haunted by spectres: pale, vicious-looking aliens who prey upon the dead to raise an army of living corpses. With the fabled Kairos Ring they can carve portals into other dimensions - and, by accident, Joshua is blown through one of them.

The TARDIS materialises on a remote island, set in a sea of acid, on the planet Marinus. The Doctor, Susan, Ian and Barbara meet Arbitan, keeper of a vast computer which rules and balances the gentle life of Marinus. Yet peace on the planet is threatened by the sub-human Voord, who wish to take control of the Conscience. Arbitan enlists the travellers to find the five crucial Keys of Marinus in various locations across the planet. Thus begins a series of terrifying adventures for the Doctor and his friends, who must find the Keys if they wish to ever to see the TARDIS again.

It's 1794, and the TARDIS materialises some distance from Paris during the French Revolution, the scene of the infamous Reign of Terror. Soon the Doctor, Susan, Ian and Barbara find themselves caught up in the tangled web of historical events. Who is James Stirling, the master-spy to whom Ian must deliver a message? What world-shattering events are being discussed in a deserted inn off the Calais road? And can the Doctor and his friends escape a violent and bloody death at the dreaded guillotine? 

In 1890s Cardiff, reporter James MacFarlane is intrigued by rumours of ‘anaesthesia frolics’, at which gatherings the latest frontier in pain relief is demonstrated to influential guests. After he speaks to someone who attended several such ‘frolics’—and left with a hand and two fingers missing—James realises that the events have a dark side. Contriving an invitation, he is astounded to find another guest also investigating—it’s his old friend the Doctor! Reunited in mystery, the Doctor and James enter the murky underbelly of polite Cardiff society.

Susan Jameson reads a brand-new original story featuring the Fourth Doctor and his companion Mrs Wibbsey. In 18th Century coastal Italy, the local fishermen haul in an extraordinary catch: a gigantic serpent. The Doctor identifies it as an alien, but to the ailing locals this fabled sea creature has the capacity to heal them - if only Count Otto will share it with them. When Mrs Wibbsey comes under the influence of the Count, the Doctor finds himself snared by the wicked power of a seemingly immortal magician, the infamous Cagliostro!