The Secret of the Frankenstein's Castle


In this adventure the players will need to rescue a pack of gigantic fruit bats from a steampunk scientist performing cruel experiments on them.

During their mission they will have to resist the allure of a sentient psychoactive tree, make their way through the dangerous bio-factory producing bizarre eldritch monsters and abominations, escape from a corpse-disassembly machine, only to confront the spider-legged mad scientist in the midst of his laboratory.

During the climactic battle they will have to dodge torrents of mutagenic sludge, and then fly away from the collapsing factory on the backs of the rescued bats.

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Frankenstein’s castle has been long abandoned, until Doctor Grimworks, the entrepreneurial heir to the castle, has turned it into a factory for producing Chimeras - grotesque combinations of corpses and various animal parts.

The Chimeras are later sold as tools to perform menial labor, to help with construction, to perform dangerous or difficult jobs (mining, lifting things, delivering heavy objects).

Dr. Grimworks has bioengineered a psychoactive tree (think gigantic Venus flytrap) to lure and trap various woodland creatures, which are then used in terrible experiments, mutated, or disassembled into parts and used to build Chimeras.

One day the tree has lured a herd of enormous (yet peaceful) fruit bats belonging to an old goblin. Valuable assets to the Doctor, priceless friends and companions to their owner.

Meeting the Old Goblin

It is a dark and stormy night. The players have been traveling through the Romanian forests for days, it’s been raining non-stop, they are drenched, exhausted, and very lost.

When a flash of lightning illuminates the path ahead, they briefly see a silhouette of a humanoid creature with gigantic bat wings sprouting from its back.

Upon closer examination, it turns out to be an elderly goblin, with an adorable baby fruit bat perched on its shoulders. The baby bat is gigantic - the size of a grown wolf, it has a broken wing, and the goblin is nursing it back to health.

Old Drew

An elderly goblin. He has raised a herd of gigantic fruit bats who help him to scour the forest in search of the elusive emerald apples, a valuable fruit that nobles will pay good coin for. Old Drew has trained these bats himself and loves them like family.

Old Drew’s precious herd has disappeared into the woods (the bat on his shoulders is the only one who has managed to return), and now he’s walking the forest and crying out the names of his beloved pets.

"Fluffy! Bertie! Milton! Fungus! Scrappy! Come here little buddy! Peanut! Where are you? Groucho! Puppers! Betty! Tootsie! Wigglebutt! Snuggles! Buck! Otto! McFlufferton!""

After noticing the players, he will beg them for help, offering a bunch of emerald apples (priceless potion ingredients) in return.

“Me family o’ bats have gone missin’ during the night! Oh I knows you may think I be mad, but me bats are me livelihood. I knew that eerie scent in da’ wood was an ill omen! Please find mah bats, they are well-trained to return to me, I know somn’ terrible musta happened if they can’t!”

Old Drew is right. There is an enchanting odor that whaffs through the trees enticing players deeper into the forest... Players can follow the scent or notice that any rare woodland creatures they see are moving in the same direction.

The Giving Tree

The players make their way to a large beautiful tree in full bloom. It’s glowing with faint golden light, emanating peace and comfort - the perfect shelter from the storm.

It has very enticing fruits which are extremely difficult to resist. The tree will speak to the players in a silky voice, inviting them to take a break from the journey and rest in its shade. It will try to convince players to taste its fruit. If they refuse - it will start crying, so distraught that the only human travelers it has met in years don’t want her fruit.

If one of the players succumbs to the temptation, the illusion will dissipate, a flower will close around their hand, ensnaring them, just like it did with many animals before.

The powerful tendrils will wrap around the player, and do their best to drag them towards an open maw at the base of the tree until they’re swallowed up!

To the Castle

Behind the tree, farther down the path, difficult to see during the storm, is the Castle Frankenstein.

The tendrils will drag the trapped player through the tree’s root system (which seems, from the inside, like a digestive tract of an enormous animal), and deliver them to the factory inside the castle, dropping them onto the conveyor belt, prompting other players to attempt rescuing them.

If the players manage to defeat the tree without anyone getting captured, as it’s dying it will direct players to the castle by saying “Guess what, my master will turn your precious bats into meat real soon."

The Mad Factory

Conveyor belts are transporting animals and human corpses, bioengineered steampunk machines are processing them, reassembling them into Chimeras.

The animals are taken from the row of cages (bats aren’t in them).

A gigantic eyeball swivels like a snake, standing on its optic nerve, examining the products. Huge tentacles (like a bionic version of Tesla factory robot arms) are dipping animals into a vat of mutagenic goo, and attaching new parts to them.

  • There’s a bionic “car” with 6 bear legs in place of its wheels.
  • A zombie with giant praying mantis legs instead of arms.
  • A wolf with a human arm in place of the head (think Spot from Boston Dynamics).
  • Huge dragonflies with buzz saws attached to their tails.
  • A DeerWolf (think CatDog) with 12 eyes.

Ahead of the trapped player, a bunny is dipped into the mutagenic goo, comes out with the lower part of its body looking like a huge hairy centipede. The player is next!

After the player has been rescued from the machine, the players see Ivan walk in.


Dr. Grimworks’ assistant. Basically Frankenstein’s monster. Friendly, polite, very sad. Wears a mind-control helmet, forcing him to obey Doctor’s commands.

Ivan will walk up to the animal cages, pick up a huge spider, and start dragging it upstairs - into the tower where Dr’s lab is in. If the players engage with him - he will notice them, act courteous and calm, politely asking them if they’re here for an appointment with Mr. Grimworks.

The Laboratory

Inside the lab, players will see Mr Grimworks.

Mr Grimworks

Entrepreneur, mad scientist, Doctor Frankenstein’s distant descendant. Looks like Mr. Waternoose from Monsters Inc.

Doesn’t see himself as evil - he just builds useful tools, makes profits, and doesn’t care too much about the animal suffering he’s causing.

Hanging from the roof of the lab are more animal cages. Among them, Old Drew’s fruit bats!

One of the bats is lying on the gurney, Mr. Grimworks uses the mutagenic sludge to glue huge spider legs to its torso.

When he notices players, he will act cheerful and excited, and launch into a sales pitch “Oh, are you here to place a pre-order on my new, top-of-the-line BatLift 9000? It can deliver even the heaviest objects to the facilities your regular WolfCarrier 500 just can’t reach!”

The Final Showdown

Dr. Grimworks won’t be willing to part with the bats without asking an exorbitant price (“they are valuable assets, I can’t just give them away for free, you understand”).

If the players try to rescue the animals by force, the Doctor will weaponize the tool he was using to operate on the bats (picture a steampunk squirt gun), to spray players with the mutagenic sludge.

The Doctor is quite agile, he can use his spider legs to run on walls and on the ceiling. Whenever the sludge hits a wall, tentacles erupt from it and try to grasp the players. If it hits a player, a terrible mutation will grow from the player armor or clothes (spider legs, crab claws, scorpion tails, tentacles, extra limbs, etc), and impede the players because of the massive weight on their body.

Some of the random mutations are beneficial - players have control over them and may even use them in combat. Some players might leave this fight with a few extra eyes, a warm wooly coat of fur, or an ability to echolocate.

Ivan will release some of the experimental monsters and they will attack the players. If the players destroy Ivan’s mind-control cap and set him free, he will do his best to help them defeat his evil oppressor. Monsters also have mind-control caps, and can be turned against their creator.

The spider-legged bat is not mind-controlled yet, once released from the gurney it will happily help the players to fight, even let a player jump on its back and fly around the laboratory.

Escape the Crumbling Castle

Once Dr. Grimworks has been defeated, he will use the last of his strength to open all cages, and activate a dead-man switch, causing the factory tentacles to go haywire and begin destroying everything around them.

The castle, now overrun with monsters and wild animals, begins to collapse. Players can jump onto the backs of the giant bats and fly away to safety. As soon as the bats are free, they will fly back to their master, Old Drew, who will be happy to reunite with his bellowed pets.

If the players have liberated Ivan from his mind-control helmet, and rescued him from the crumbling castle, he will become their loyal friend and ally.

Adventure Writers’ Room

This adventure was made by the Adventure Writers’ Room.

We are a group of GMs who meet in the discord voice chat, and challenge ourselves to improvise a one-shot adventure (like this one) in 2 hours.

We’re looking for some friendly and creative people to join us!

Join our Discord here.

See the other adventures we have created here.

Authors: Lumen, Flute, Mr.Peculiar, The_Tale_Spinner, heyzoms.

Art: Jesse Pak, Sebastian Ramos, Jonathan Fletcher, Anthony Fylladitis.

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