The Twelfth Doctor, still refusing to change, goes on a last adventure with the First Doctor.

In a South Yorkshire city, Ryan Sinclair, Yasmin Khan and Graham O'Brien are about to have their lives changed forever, as a mysterious woman, unable to remember her own name, falls from the night sky.

Still reeling from their first encounter, can the Doctor and her new friends stay alive long enough, in a hostile alien environment, to solve the mystery of Desolation? And just who are Angstrom and Epzo?

Montgomery, Alabama, 1955. The Doctor and her friends find themselves in the Deep South of America. As they encounter a seamstress by the name of Rosa Parks, they begin to wonder whether someone is attempting to change history.

The Doctor, Yaz, Graham, and Ryan find their way back to Yorkshire only to find something is stirring amidst the eight-legged arachnid population of Sheffield.

Yasmin travels in time to visit her grandmother during her youth in the partition of India, but everyone gets caught up in the tragic bloodshed of that era.

A mysterious message arrives in a package addressed to the Doctor, leading her, Graham, Yaz and Ryan to investigate the warehouse moon orbiting Kandoka, and the home of the galaxy's largest retailer.