A three-man rocket crew are nearly done with their mission to Titan Base until a course change puts the rocket in the path of a strange cloud in space. By the time they arrive, they have come under the control of a sentient virus which threatens the galaxy. When the TARDIS picks up an emergency message, it flies into the cloud, infecting the Doctor. To save himself and others, he must undertake a dangerous journey.

“Contact has been made!“ A relief crew en route to Titan in 5000 AD unwarily pick up hitchhikers that change them. Shortly thereafter the Doctor, passing through the same point in space, is hitchhiked as well, but not Leela - a reject who must die.

On Earth in 2018, the Doctor and his companions are enmeshed in a deadly web of intrigue thanks to his uncanny resemblance to the scientist/politician Salamander. He is hailed as the "shopkeeper of the world" for his efforts to relieve global famine, but why do his rivals keep disappearing? How can he predict so many natural disasters? The Doctor must expose Salamander's schemes before he takes over the world.

Jeffrey Clavering is hired in London by The Great Eastern Oil Corporation to go to Paris to prevent unscrupulous industrialist Nikolai Kamarov from gaining control of their oil fields and turning them over to a foreign power.

In Ukraine, on the 26th of April 1986, a catastrophe shook the whole of Europe, and the world experienced a fatal day that became engraved in its history – A major nuclear accident at Chernobyl turned an entire city into a post-apocalyptic ghost town. Tens of thousands of lives were ruined. Today, nature has begun reclaiming the area of the exclusion zone surrounding the old power plant. But the consequences and the suffering are still felt today. Chernobyl is a lesson for the present. It warns us about the risks of our ever-evolving modern society. But Chernobyl taught us more importantly about the cost of lies. By highlighting the flaws in the Soviet Union system, it revealed how they can lead to disaster, and how the way we tell information about what really happened can cause harm. The past cannot be undone, but we can learn from it.

In April 1918, a disease of unknown origin swept across the five continents. In 18 months, millions of lives that had not been taken by the war were swept away by a virus that would cause the worst pandemic in history: the Spanish flu.

The Doctor contemplates a journey to see an old acquaintance and digs a well. Released in cinemas alongside the 3D double-bill of Dark Water and Death in Heaven.

The Doctor, Jamie and Zoe return to Earth and become embroiled in the schemes of Tobias Vaughn. They meet up with an old friend, Colonel (now Brigadier) Lethbridge-Stewart, and some old enemies, the Cybermen.

The TARDIS returns Tegan to Heathrow Airport: Tall trees, peaceful, clear skies, thriving vegetation and a touch of sulfur in the air. Obviously the TARDIS is a little out of date (about three hundred years or so), but upon looking around the Doctor finds there's more amiss than his navigational controls, all arising after a recent comet crash that was not on Earth's schedule.

The TARDIS crew take up residence near Rome in 64AD, where Ian and Barbara are kidnapped by slave traders, and the Doctor's imitation of Maximus Pettulian sees him taken to the court of Emperor Nero where he inadvertently plays a part in deciding the course of history...