A two-part adventure begins with the Doctor (Matt Smith), Amy (Karen Gillan) and Rory (Arthur Darvill) crash-landing the TARDIS.
Despite the retro soundtrack – who knew that the Doctor was a Dusty Springfield fan? – they are many years into the future at a factory where clones who share the physical form, memories, genetic make-up and clothes of their human ‘originals’ are sent to mine dangerous acid under the watch of feisty Foreman Cleaves (Raquel Cassidy).
The clones, known as ‘Gangers’ regularly die in the mines, whereupon new clones are produced – leading to numerous debates over what constitutes a human.
When a solar tsunami frees the Gangers, the Doctor must intervene to try to prevent war between the humans and their clones. Rory even makes a stand after one of the Gangers, Jennifer (played by Sarah Smart) befriends him, putting his life on the line to protect her.
Can the Doctor help build trust between two apparently identical sets of people?
And how will the Time Lord react when he comes face-to-face with his own Ganger, forged out of strange, amorphous, milky substance? All will be revealed next week.