"One" is the 1048th episode of Casualty and the 44th and final episode of the 31st series. It was preceded by "Somewhere Between Silences - Part Two" and followed by "Episode One". The episode was directed by Jon Sen and written by Paul Unwin. This episode was special, in that the entirety of it was filmed in one single shot by a handheld camera.
Although the episode wasn't filmed and aired live, it was filmed in one take, as one hour long scene. Filming took place in April 2017, concluding on the 13th.
The episode received mixed reviews from critics and fans alike. Some viewers praised the effort put into the episode by cast and crew, whilst others criticised it, claiming it made them feel dizzy and sick.
- This episode is Duffy's first centric episode since series 17's "The Point of No Return".
- Noel Garcia, portrayed by Tony Marshall, is the only main character not to be in the episode.