Yasmin (Mandip Gill), while celebrating the birthday of her grandmother Umbreen (Leena Dhingra), receives a broken watch from her. She asks the Doctor (Jodie Whittaker) to take her, along with Graham (Bradley Walsh) and Ryan (Tosin Cole), back to the Punjab in August 1947, when the watch was broken. There, she learns that the watch’s previous owner was a Hindu man named Prem (Shane Zaza), who is getting married to the younger Umbreen (Amita Suman) despite the fact that her family is Muslim.
Unfortunately, it is the day before the Partition of India. To avoid involvement in the turmoil of that day, the Doctor advises the family to rush the wedding ceremony. However, two alien creatures are seen standing over the body of the wedding overseer Sadhu Bhakti (Bikranjit Gurm), The Doctor had seen them before, when she had head pains.
They are joined by Prem, who had also had a vision of them around the time of his brother’s death in World War Two. The Doctor recognizes them as Thijarians, a race of assassins from whom she stole a capsule out of their ship. But she learns that they are actually the last of their kind. The capsule held the remains of their destroyed planet, and they now commemorate those who die alone. The Thijanians—Kisar (body of Nathalie Curzner, voice of Emma Fielding) and Almak (body of Barbara Fadden and voice of Isobel Middleston)—reveal that Prem will be a victim of the Partition. They show the Doctor the death of Bhakti and she learns that he was killed by Prem’s younger brother Manish, who opposes the mixed marriage.
The Doctor oversees the ceremony and they see the watch being broken. She confronts Manish about Bakti’s murder and he reveals that he contracted a gang of Hindu nationalists to attack the reception. Umbreen and her mother escape, but Prem remains behind to reason with Manish and is killed by the nationalists while the Thijanians observe.
The episode was written by Vinay Patel and directed by Jamie Childs, and it received positive reviews. It was generally liked and was praised as different from the usual Doctor Who story. The music was played on the standard Indian instruments, the tabla and the shehnai, as was the closing theme by Shahid Abbas Khan. It was filmed in Spain. This was the 150th episode of the 2005 revival of Doctor Who, starting with Christopher Eccleston. Scary-looking aliens who turn out to be noble is a fairly common plot device for this Doctor—part of her general niceness.