When Harry Winter goes out collecting rocks to repair the wall around his father's farm, he makes a fatal mistake. He disturbs Lucifer's Tombstone, and awakens something demonic and dreadful... The TARDIS arrives in the 18th Century village of Thornton Rising in the Yorkshire Moors - a village cut off from the world by an all-consuming darkness, where the sun has not risen for three weeks.

Toby Longworth reads this original adventure for the Thirteenth Doctor and Graham, as played on TV by Jodie Whittaker and Bradley Walsh. It's 1970, and record-breaking explorer Silvia Sandstrom has completed an epic lone drive to the North Pole. But as she activates her on-board experimental equipment, her vehicle is swallowed by a massive hole in the ice. Meanwhile the TARDIS is drawn to an arid wasteland, also apparently at the North Pole. There the Doctor and Graham meet Silvia - but it's clear that she is a woman out of her own time.

The Doctor, Amy, and Rory are awe-struck by their first sight of Hope Eternal, a super-earth bigger than Earth itself with heavy gravity, volcanoes, and a crust loaded with mineral deposits. But their wonder is cut short when they discover a body dumped on the ground - a huge figure with extraordinarily long arms covered in thick, purple scales. Yet the corpse is not alien: he's human, albeit unlike any human Amy and Rory have ever seen.

Thrown off course by a howling storm, the TARDIS lands in a bleak, desolate stretch of countryside. The Doctor deduces that it has arrived in Hampshire in the 1920s and, sniffing the air, he smells a distinct odour of sulphur - indicating that a spaceship has crashed in the area. While Rory goes to fetch an umbrella, Amy and the Doctor brave the rain to find the stricken craft. It is huge, shiny, silvery-blue - and completely empty. A set of footprints leads to a cosy-looking, old-fashioned cottage: but the house, too, is deserted.

When the TARDIS is buffeted by "time slippage", the Doctor experiences a terrible vision of the end of everything. Tracking the source of the disruption, he takes Rory and Amy to what appears to be an English public school in the 1950s. But the friends discover that there are some very unusual things about Darkstar Academy. For a start the prefects carry guns, and then there is the strange force field that surrounds the perimeter. Not to mention the foot-long, crab-like creatures with spiny, armored bodies....