Catacomb Runners

Short version:

Street Children - Thieves/Smuggler - Zoogs
Leader: Kavzar (Adult transformed into Zoog by bite) / Dr Charles Jekyll
Goal: Open an orphanage for poor children -> transform them in Zoogs
Allied with: Sons of the rat god
Dramatis Personae: Duel-master: Captain James Macnamara & Mama Browny (16y.o. Mestiza)
Peculiarities: Spy & deliver material and messages to the highest bidder (lots of kids in the streets - they are practically invisible in the masses)
Secret: Mr Charles Jekyll doesn't mean anything bad for the kids. Only Kavzar, his zoog alter ego, wants to convert the kids to build an army. Furthermore, nobody knows that zoogs exist.

Long version:

These are the poorest souls of London. They live by themselves, trying to get by on a day to day basis, not having a childhood at all.
But the smartest of them have been recruited into the catacomb runners for a roof over their head at night and a guaranteed meal every day.
For that, they have to learn to use the catacombs and sewer system to get everywhere unnoticed within London. They work as couriers and smugglers. The contracts are handled by Mama Browny and half the money is collected by Dr Jekyll to invest in an Orphanage (which is already in construction).
Mama Browny is the real front person of the organization. She doesn't know anything about the zoogs (these are humanoid giants rats, as long as they are underground)
Captain James Macnamara is their protector. If anybody harms one of the kids, they have to report it to Mama Browny. The unsavory character will have to answer for his acts. If James deems them guilty of misconduct against an orphan, he will challenge them to a duel (and he is a very deadly fellow)
On his side, Dr Jekyll petitions the government and the royalty to create an institution for street children, with not a lot of success, apart from building his own orphanage.
To contact the catacomb runners, you have to ask a street kid when his last meal was. If the kids answers "yesterday when the 3rd bell chimed", you have to offer him a loaf of bread. The kid will then arrange a meeting with Mama Browny in a neutral area.
Their alliance with the sons of the rat god is more a non aggression pact than a real alliance. If they meet in the catacombs or sewers, they will try to look the other way as much as possible.
Only a few kids have already been transformed in Zoogs

Typical member:

Street kid:
STR 7 - DEX 13 - Will 12
Wearing rags and smelling bad
1 knife (for the kids older than 12)

Captain James Macnamara:
STR 14 - DEX 16 - Will 8
Sword and 2 Pistols
good horse and long covering clothes

Sources:

- Zoogs are present in the French translation of Into the ODD (in the supplemental material developed for the kickstarter) but first appeared in "Everyday is Halloween" (same editorial team). I took the liberty to give them a warhammer-ish Skaven feel.
- Dr Charles Jekyll is the fictive grandfather of the infamous Dr Henri Jekyll popularized by Robert Louis Stevenson.
- Captain James Macnamara is an historical figure (one of the best duellist of his time - not supposed to be in London, though).