Parts: 1 (45-minute)
Writers: Malorie Blackman and Chris Chibnall
Airdate: 21 October 2018
Production Code: n/a

Doctors: thirteenth
Companions: Ryan, Yaz, Graham

Story: The Doctor's attempts to return Ryan, Yaz and Graham to Sheffield are interrupted when the TARDIS runs across unexpected artron energy readings in 1955. Feeling she should investigate, the Doctor leads her companions into Montgomery, Alabama, in the middle of the Jim-Crow-era South. Her companions are initially overjoyed to be exploring the real 1950s, but this rose-colored view of the world is swiftly shattered when Ryan is viciously slapped for attempting to return a white woman's glove... and is rescued by none other than Rosa Parks.

Realizing that Rosa has been exposed to artron energy, the Doctor swiftly determines that she and her friends need to figure out whether Rosa is in any danger... because tomorrow is the day that she's due to make her fateful bus protest, refusing to give up her seat to a white man, and any change to history could derail the entire US civil rights movement...