This season of Doctor Who has already made waves for presenting the world with the first female Doctor. The waves of change have kept coming thanks to Sunday’s episode, which featured an uncompromising look at the monumental stand civil rights activist Rosa Parks took against segregation in Montgomery, Alabama, by refusing to move from her bus seat.

The episode, “Rosa,” features the Doctor (Jodie Whittaker) and companions Graham (Bradley Walsh), Yasmin (Mandip Gill) and Ryan (Tosin Cole) traveling back in time to 1955 with the goal of preserving the events that happened between Parks (Vinette Robinson) and Montgomery police before a nefarious presence tries to change history’s trajectory forever. The episode was co-written by author Malorie Blackman, the series’ first Black screenwriter and sixth female writer. Thankfully, Blackman won’t be the only woman or person of color to write for the series this season, since showrunner/writer Chris Chibnall has assembled a racially and gender-diverse writers room.

This episode is the first in the history of all 37 seasons of #DoctorWho that was written by a person of color. Malorie Blackman, who wrote this, is only the 6th woman to write an episode. It’s immediately the most iconic episode in my book. It’s really fantastic. So powerful. https://t.co/qUc0zyDq2F

— Travon Free (@Travon) October 22, 2018

Fans of the show were overwhelmed by the episode, expressing their gratitude on Twitter. Particularly noteworthy is how the episode compared 1955 to today, showing how many of the remnants of racism still remain. In one scene, Yasmin and Ryan discuss how police brutality and discrimination still affect their everyday lives.

Tears as Doctor Who meets Rosa Parks in ‘bold’ and ‘uncomfortable’ episode

Overall, “Rosa” is an episode that shows just how universal Doctor Who can be, as well as its potential to embrace one of the tenets of science-fiction, which is to point a mirror to our society and how it can and must change for the better.