4 actresses/singers are invited to take part in a Netflix project in which a fictional girl group will be formed.

Ahn Hyejin and Kim Yongsun, who worked together in a series before, have been dating for 2 years.

One is a successful solo singer since she was 15 and the other is famous for doing musicals and Korean dramas.

Moon Byul-YI is a songwriter, singer and producer since she was 16 and Jung Whee in is a natural talent found by the producer of the show.

The four girls are Korean but grew up in the USA.

In the series, Byul's character gets romantically involved with Yongsun's and the same happens with the other two. 

The problems start when the unnies show too much chemistry despite not liking each other much, and Hyejin feels jealous.

Four strong personalities and huge talents that will accidentally shape a phenomenon called Mamamoo and a lot of backstage drama.