Stranded without a ship and still missing Alebrije, the gang (now joined by Marcella) tumble into foggy London and uncover a plot that's robbing orphans of their teeth.
Tropes:
- Dark Is Not Evil: Dr. Blackpulp is blunt, intimidating, and very obsessed with teeth, but he's not behind the stolen teeth. He's actually investigating the matter on behalf of the Crown.
- Not Evil, Just Misunderstood: The Bactus are only stealing the teeth out of people because they need to eat them to live. Once Leo and the others realize this, they're able to negotiate and work out a compromise.
- Orphanage of Love: Being mistaken for street kids, Leo and Marcella are taken to an orphanage run by a kind woman. However, it is infested with the Bactus, who try to steal their teeth at night.
- Solid Gold Poop: The Bactus literally poop out gold as a byproduct of eating teeth.
- Tooth Fairy: The Monster of the Week are the Bactus, insectile, tooth-eating creatures loosely based on the "tooth trolls" from Karius and Bactus. Teodora convinces them that, with an image change, kids will give them unwanted teeth.
- Toothy Issue: Children all over London are missing most of their teeth.
