As a "mudlark," the orphan, Eel, spends his days in the River Thames, searching for odds and ends to sell. As if being an orphan isn't hard enough, Eel is hunted by Fisheye Bill Tyler, the nastiest man on the streets. Add in a secret that costs Eel four shillings a week to keep, and an outbreak of the "blue death," and Sonlight resource: https://www.sonlight.com/products/the-great-trouble