The sci-fi thriller is based on the Korean webtoon of the same name by Hongjacga. Lee Sun-kyun stars in the lead role as a brain scientist trying to solve the mysterious death of his family by hacking into the brains of the deceased. The series is the first Korean-language show produced for Apple TV+. It debuted on November 4, 2021, to accompany the streaming service's launch in South Korea. On January 27, 2022, multiple official sources stated that the series would have a second season.
After losing his family in a mysterious accident, Sewon, a brilliant brain scientist, tries to solve what happened. He performs "brain syncs" with the deceased in order to search for clues hidden in their memories.