Code Black is going musical.

The cast of the CBS medical drama will be dusting off their pipes and putting on their dancing shoes for an elaborate early season three musical number, ET can exclusively reveal.

The majority of the ensemble -- including Marcia Gay Harden, Luis Guzman, Harry Ford, Benjamin Hollingsworth and Boris Kodjoe -- will be performing in the number, which will open the second episode of the new season. Rob Lowe and Moon Bloodgood will not be in the routine, which is set to Hozier's "Angel of Small Death and the Codeine Scene."

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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.

What's the context for the musical detour?

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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.

Code Black premieres midseason on CBS.

For more, watch the video below.