The Mystery of the Jewelled Moth is the second novel in The Sinclair's Mysteries series by British children's author Katherine Woodfine, publishing by Egmont Publishing in February 2016.

The novel is the second book in a four-book mystery-adventure series set in Edwardian England.

[2] Sophie is an orphan who has been left penniless when her father dies, due to an error in the will.

In The Mystery of the Clockwork Sparrow, Sophie finds a job in the millinery department of Sinclair's Department store, Londons newest and greatest, and makes friends with Billy, a junior porter with an uncle already working in the store, and Lil, a "mannequin" by day and an aspiring actress by night.

In The Mystery of the Jewelled Moth, the Jewelled Moth, a priceless piece of jewellery, disappears, and again Sophie, Lil and Billy have to solve the mystery, this time by infiltrating Lord Beaucastle's fancy dress ball.