The Eyeball Collector by F. E. Higgins

Although Hector Fitzbaudly has always lived a plush life on the posh side of the River Foedus, he’s yearned to slip away from his comfortable home and see the seedy side of Urbs Umida. Unfortunately, he gets his chance when a blackmail artist confronts his father with a terrible secret from his past, and Hector finds himself penniless and on the streets. He is determined to get his revenge against the man responsible, who has been a pauper, a gentleman, and an Eyeball Collector—stealing jewels from the wealthy to make false eyes to replace his missing one. He is a master of disguise, and a swindler who moves from place to place.  Hector trails the Eyeball Collector to the small village of Pagus Parvus and the foreboding Withypitts Hall, run by the eccentric Lady Mandible who has a strange taste for the macabre. He takes a job incubating butterflies for Lady Mandible, and places himself in the perfect position to take revenge. Hector is so close to the Eyeball Collector, but will he be able to go through with his plan?