As the Unsung Heroes, a choir of migrant domestic helpers rehearses for a performance of "I Wish I Could Kiss You Goodnight," a song with a poignant message to the children they've left behind in Indonesia and the Philippines while they work to support them financially from prosperous Hong Kong, we follow the stories of these women, peering behind the masks of their bravery to explore the hardships and exploitation they suffer, their vulnerability within the city and the challenges they overcome.