The Doctor takes her companions on their first journey back in time – to the dangerous, racially segregated world of Alabama in the 1950s. They encounter one of the era’s heroes, black civil rights campaigner Rosa Parks, but also discover a plot to change the course of history. Vinette Robinson (Sherlock, The A Word) guest stars in an episode by children’s author Malorie Blackman.
Alabama. 1943. Rosa Parks enters a bus from the front, intending to sit in one of the seats marked for “colored” people. She is reprimanded by the bus driver and told to enter the bus from the back, as she is meant to. She tells him that it seems logical for her to find a seat now instead of leaving the bus just to enter through a door that is currently blocked by standing passengers. The bus driver yells at her, forcing her to exit the bus. As she attempts to re-enter the bus through the rear door, the driver closes the doors and drives away, leaving her to walk home.
12 years later, in 1955, the TARDIS lands in an alley in Montgomery Alabama. She says they’ve nearly made it. After what appears to be the 14th attempt, they have made it to Earth. Graham asks if she can control the TARDIS. The Doctor responds that she can, but sometimes it has a mind of its own. They exit the TARDIS and decide to have a look around when The Doctor notices an unusual amount of Artron Energy found there.
As the team walks through Montgomery, Alabama searching for the source of the Artron energy, a woman drops her glove. Ryan picks up the glove and tries to give it back to her. When he does, the woman’s husband turns and slaps Ryan. He yells at him to never speak to a white woman. Rosa Parks intervenes and is able to diffuse the situation. She warns the team that a boy from out of town had been found dead after speaking to the wrong person, telling them to be careful. When she introduces herself as Rosa Parks, the team is star-struck. The Doctor slips that she is a big fan, then quickly corrects course, saying that she is a fan of Montgomery. When Rosa leaves, The Doctor states that Rosa is apparently surrounded with Artron energy.
Cut to the alley in which the TARDIS had landed. A man in a leather jacket and jeans approaches, trying to get inside. He shoots the TARDIS with a strange weapon and comments that there is a force-shield. Meanwhile, the TARDIS team sits in a bar discussing their next move when they notice that the room has suddenly become very quiet. The waitress approaches and says that they don’t serve “negroes” in that establishment. Ryan smarts off, responding, “That’s good, because I don’t eat them.” The waitress then calls Yaz Mexican, apparently unaware that she is Pakistani. The team leaves the bar.
We soon find the team at the bus depot. The Doctor unlocks a large door and enters what appears to be an abandoned space. Within the space, they find a case that had been hidden by a perception filter. Within the case, they find various bits of alien or future technology. The Doctor finds a device that she says is the battery for some kind of device, but is unable to say what before they are attacked by the man in the leather jacket. They run outside and hide behind a tanker. The man climbs atop one, and The Doctor climbs on top of another. The two have a discussion in which the device is revealed to be a Temporal Displacement gun. The man says his name is Krasko. He has used a vortex manipulator to get to that time, but is apparently unable to leave. Judging by a tattoo on his wrist, he had been released from Stormcage prison, one of the highest security facilities in the universe, and the same prison from which River Song had escaped numerous times. He reveals that he was there for the murders of roughly 2,000 individuals and had been released at the end of his sentence. He warns The Doctor that she should leave before he kills them. As they go, she tells the team that there is no way they are leaving.
Next, the team finds itself at a motel with a sign reading, “Whites Only”. Ryan says that he is sick of seeing that sign. They sneak Yaz and Ryan into the motel through the bathroom window and begin discussing what they plan to do next. They hear a knock on the door causing Yaz and Ryan to flee through the bathroom. At the door is a police officer. He mentions that he had heard that there were a couple of British people in town with some that he described as “mongrels”. The Doctor states that she doesn’t know anyone who fits that description. The Police officer kicks open the bathroom door and sees that there is no one there or in the back alley. He leaves. Yaz and Ryan are crouched behind a dumpster in the alley and have a deep conversation about the experiences that they have had with racism in their own lives. They state that things are better, but that there is still a long way to go. Graham alerts them that they can re-enter the motel. When they do, the team continues their planning. They state that it appears Krasko is trying to nudge history to change how Rosa Parks affects civil rights. They plan to find out everything they can about Rosa’s routine so they can make sure she is on the bus at the right time to do what she needs to for history. Graham mentions that he wishes Grace were here, as she loved Rosa Parks, owning a shirt that said, “Spirit of Rosa” on the front. Ryan states that he doesn’t because she would start a riot. Graham also mentions that Grace had told him the bus driver’s last name was Blake and was called Blake the Snake.
That night, the team rides the bus and speaks to Rosa to discover where her stop is. When she gets off, Ryan follows her to get more information. He is discovered and joins her in a meeting with other leaders of the civil rights movement, including Martin Luther King Jr. He is in awe of the fact that he has found himself speaking to two of the biggest civil rights leaders in history. Meanwhile, Yaz works to get as much information as she can about where Rosa works, and The Doctor returns to the bus depot. There, she finds Krasko. She discovers that she can’t hurt her or anyone due to an implant that would cause him pain if he tried. This is reminiscent of the device placed inside the head of Quill in the spinoff series, Class. She tells him that as long as she is there, he won’t succeed. When they all meet back at the motel, Graham reveals that another driver has been given Blake’s route because he is going to go fishing.
The next day, Yaz and The Doctor tell the new driver that he has won tickets to a Frank Sinatra concert and must leave right away. Meanwhile, Ryan and Graham convince Blake to go back to work and run his route. At the bus depot, Krasko has destroyed Blake’s bus. That night, The Doctor and Graham steal a bus and pick up Blake at the depot, telling him that he can run his route. At the same time, Ryan works to get people to continue waiting for the bus and Yaz is with Rosa Parks to make sure that she gets to the bus on time. Ryan confronts Krasko. Krasko tells him that they will be too late. He says that they will be three passengers short to get the driver to ask Rosa to move. He says they have lost. Ryan uses the Temporal Displacement weapon to send Krasko to the past. When he gets on the bus, he tells The Doctor and Graham that he has done his best.
Shortly, Rosa and Yaz get on the bus and take seats. The bus fills. When they reach the stop at which Rosa is arrested, The Doctor counts seats and stays. Graham tells her it’s time for them to go. By this time, he has gotten up and someone else has taken his seat. The Doctor tells him that if they get off, there will be no reason for the driver to ask Rosa to move. She says they cannot leave. Graham says he doesn’t want to be a part of it. He is now the passenger that spurs Blake to tell Rosa that she must move seats. She refuses. As she is yelled at by Blake, The Doctor, Graham, Yaz, and Ryan are forced to allow it to happen without helping. Rosa is arrested.
Back in the TARDIS, The Doctor explains that the future is intact and that Rosa inspired the civil rights movement and later received a medal for her actions. She says that she changed not only the Earth, but the universe, showing them an asteroid that has been named Rosa Parks…