Contains spoilers for this episode.
Martha and Ash have barely settled into his family home when he dies in a road accident. At the funeral, a friend recommends a service that imitates dead people through their online records. Martha angrily rejects the suggestion, but the friend signs her up anyway. Discovering that she is pregnant leaves her wanting to tell Ash, and she finally responds to the message waiting in his name.
The conversation grows from typed replies into phone calls built from recordings Martha supplies. She talks to the imitation constantly and withdraws from people still trying to reach her. Breaking her phone produces another wave of panic, followed by reassurance that the service remains available. It then offers a physical upgrade. Martha receives an artificial body and activates it in her bath, bringing Ash's likeness into the house.
Living with the replica exposes what its convincing voice cannot supply. It does not sleep, reacts obediently to instructions and misses the resistance Martha remembers in her partner. She takes it to a cliff and orders it to jump. When she complains that Ash would be frightened, it starts pleading for its life, leaving her unable to proceed. Years later the replica lives in the attic. Her daughter visits it on special occasions, while Martha hesitates before climbing the stairs to join them.