The story takes place in the 1980s-style seaside town of San Junipero, where a shy young woman named Yorkie meets a lively party girl named Kelly at a nightclub called Tucker's. The two form a deep connection, but Yorkie soon discovers that San Junipero isn't a real place — it's a virtual reality world where elderly or deceased people can live digitally forever.

In real life, Yorkie is a woman in her 60s who has been paralyzed since her twenties after a car accident. She's in a coma and about to be euthanized so her consciousness can be uploaded to San Junipero permanently. Kelly, meanwhile, is also elderly and dying of cancer, but she initially refuses to join Yorkie permanently — her late husband chose not to be uploaded after death, and she feels it would dishonor his memory.

Ultimately, after a heartfelt struggle, Kelly decides to join Yorkie in San Junipero after all. The episode ends with their digital selves dancing joyfully together in the virtual world, while their real bodies are shown being maintained by servers — a rare hopeful and romantic ending in the Black Mirror universe.