Weird Wild West Part 3 - Ethan Somerville - Bog

On the hill overlooking Mojo Town looms the decaying edifice of the county orphanage, home to all the area's unwanted children. Brother and sister, Sissy and Zak Spindler, are paid to look after them and keep them safe. They seem to be doing a good job, for the youngsters are neither seen nor heard.
Unwed mother Louisa Bigelow drops her newborn son Nathaniel off in the dead of night, and then leaves town in tears. One day she hopes to return with enough money to take Nate back and give him the life he deserves.
But Sissy and Zak have other plans for the new baby delivered into their arms. In the dank basement of the crumbling mansion lies a freakish laboratory, where Sissy uses her surgical skills to corrupt innocent lives with a primordial ooze known as the Stuff.
Mojo Town's unwanted youngsters have been transformed into horrific freaks.
Only one child has not been affected by the Stuff: a fiercely intelligent boy named Bart. But Sissy considers him a failure, and treats him lire a servant. Bart befriends little Nate, already affected and transforming into a cat-boy, and together they attempt a miraculous escape to track down Nate’s mother.
But Sissy and Zak have a very long reach. Can Bart's brilliant mind help him and Nate to elude their evil clutches? Or will they be dragged back into the horrific plan Sissy and Zak have for the monstrous mutations they have created?