"My First Day" is the 591st episode of Casualty and the first episode of the 22nd series. It was preceded by "To Love You So" and followed by "Charlie's Anniversary". This episode marks the first appearances of Ruth Winters and Toby De Silva, portrayed by Georgia Taylor and Matthew Needham, respectively.
Doctors Ruth Winters and Toby De Silva join the emergency department and have very different experiences during their first day on the job. While the former gets off to a confident and stress-free start, the latter has an explosive introduction to his new duties when he treats people following a major incident.