ET exclusively debuts four on-set photos during production on the musical number (one of which you can see above), which was filmed Monday and marks the first time the cast will be singing and dancing.
In the episode, a 30-year-old woman comes into the ER with a small tumor in her abdomen, smiling and seeing things. From her point of view (translation: in her own head), she sees the doctors and nurses all dancing and singing in the ER to the Hozier song. Then, she wakes up and the doctor starts talking to her again as a patient.
Code Black takes place in an overcrowded and understaffed emergency room in Los Angeles, and is based on the 2014 ER documentary of the same name by Ryan McGarry.