Emma was born in Cheapside, London into a family of six children, with a mother who sold peppermint water in the East End for a living and a father who passed away at some point. From an early age, Emma began to earn her keep by sewing.
One evening, fourteen-year-old Emma ran out of candlelight in their home and went outside to sew by the light of the gas lamps. There, she was killed by a man affiliated with the Pandemonium Club. She was stabbed in the abdomen using a knife with an engraving of the club's symbol: a double ouroboros. Emma got ahold of the dagger before she ran from her murderer. A Shax demon was sent after her to verify her state, but she was able to hide in an alley where she ultimately bled to death.
Because the Shax demon that went after Emma was killed by Will and never made it back to report to the Dark Sisters, the sisters had Tessa Gray Change into her—with the use of Emma's pink hair ribbon as a guide—so that the former could access her memories. After experiencing Emma's stabbing through the Change, Tessa was torn out of Emma's form and left her bloodied like Emma had been in her last moments, as if she herself was stabbed—an experience Tessa compared to one she had some time before, when she Changed into a woman who had died of a gunshot wound, which caused the woman's blood to pour from Tessa's Changed body just before the Change ended. The Sisters were instantly pleased when they learned of her death.
Tessa later again Changed into Emma, this time from memory, when the Dark Sisters tied her to her bed. Emma's small frame allowed Tessa to easily slip out of her restraints. Tessa was later able to relay the story of Changing into Emma for the Sisters to the Shadowhunters of the London Enclave, who in turn told her about their own investigation into Emma's death.
Emma was quite undernourished, almost frail and was a generally thin and small girl with very fair and thin, fine hair, pale, chapped skin, and bitten fingernails.
- Clockwork Angel (first and only appearance)