Memories of Holdenshire: Into the Barrowdeep
At the end of the trail is a sizable mound. Read or paraphrase the following.
The trail has led you to a stone barrow, crouching at the foot of a forested hill. It once had a stacked-stone walled courtyard, but most of it has crumbled or been harvested for building material and now the area is choked with stinging nettles, thistle, and other vegetation. There is however a worn wagon path leading up to the entrance, with a very familiar covered wagon parked in front.
The barrow is literally straightforward—a path with no diverging passages starts with the small antechamber and leads straight to first the minor and then the main burial chamber, now the inner sanctum of the cult (Area #4). Several sets of stairs lead downwards that divide it up into the following sections.
#1: Antechamber
Cultists aren't the only creatures who see the utility in tunnels: there is also an ankheg from a nearby colony looking for a good spot for a new queen to lay her spawn. It's hungry from its underground journey and is laying low here waiting for a meal to walk by. The monstrous insect waits 5 feet inside and 10 feet underground, waiting to explode upwards as soon as it senses a creature directly above it.
#2: Minor Burial Chamber
There are 5 cultists clearing out a partial collapse here (caused by the ankheg in Area #1), directed by 1 cult fanatic . These people have been so single-minded in their devotion (on account of mind control) that they haven't taken proper care of themselves—they've been in this state longer than the adventurers and are suffering from 2 levels of fatigue because of it. Anyone that makes a DC 12 Medicine or Survival check confirms this.
Adventurers can make DC 13 Insight checks to realize that these people have been mind controlled, likely in the same fashion as the party themselves were. Now is a good time for the Narrator to remind the PCs that an attacker who reduces a creature to 0 hit points with a melee attack may choose to knock their target out instead of kill them. Otherwise, the cultists and cult fanatics zealously fight to the death.
The adventurers can also make a DC 13 Nature check to deduce that this damage was indeed caused by the ankheg . On a result of 15 or more they realize that this means that an ankheg colony is soon going to be on the move.
#3: The Landing
There are no cultists here but there are clear signs of their work, poor as it is. In fact they may have even done more harm than good. Best walk carefully or the whole place might come down!
Upon seeing the damage, any adventurer who wishes to reroll the Nature check from Area #2 may do so.
#4: Inner Sanctum
Orfrain Cassar was the one responsible for obtaining "initiates" for the cult in Northminster and has come out to the Crawley Hills to start his own branch. He's heard of the original cult's fall and has since been "recruiting", with the plan to infest or mind control his captives once the khalkos he's been paracitized with is fully grown (though of course he personally will be quite dead by then). When the adventurers reach this room, read or paraphrase the following.
The main burial chamber has been converted to an inner sanctum, set up with makeshift pews and an altar that make it look like a cruder version of the complex you all woke up in not so long ago. Standing behind the altar is a dark-robed figure who turns slowly, gradually revealing the golden-wing sigil emblazoned across its front.
"Well if it isn't our little lost lambs, come back to the fold. How lovely," he says with a beatific smile. "Don't worry, our master left me a gift so that I could start my own family. Stay, let me share it with you and we'll be one again."
Distantly, from a smaller burial chamber to the figure's right, comes a clamor of voices—among them is Belton's. "Get me out of this hellhole!"—and is that Captain Crestveil yelling that this is a trap?
Orfrain will not initiate combat, but he does expect the PCs to join his cult and wait patiently to be infected. If this offer is flatly refused or if the party attacks, he flies into a rage. He's not alone here, either—5 cultists are in the smaller burial chamber to his left and join the fray as soon as the fight begins. At the beginning of his first round of combat Orfrain perishes in spectacular fashion, allowing a khalkos spawn to emerge from the gore (he otherwise uses the statistics of a cult fanatic ) and take its own turn as though it had just used half its movement to stand up from being prone.
Suddenly Ofrain begins to scream, clutching his head and crying ecstatically "It's come! Finally it can come forth and spread its—" but he's cut off as his skull cracks with a sickening sound. His body falls to the floor with a lifeless thump, a humanoid wasp-like creature pulling itself out of what remains and chittering hungrily.
#5: Holding Cells
This area has been crudely converted from a set of small tombs to a set of holding cells. Five unfortunate victims ( commoners ) as well as Belton and Captain Crestveil are being held here.
#6: Sleeping Chambers
This is where the cultists have been getting sleep (what little they've been able to, anyhow.) Even Ofrain himself has been staying here amongst the same ratty bedrolls as his "followers".
Treasure
Between the grateful captives and the treasures of the cult, the PCs find a bag of holding , a citrine statue of a khalkos (worth 50 gold), a gold necklace with the cult's wing symbol (worth 75 gold), and 100 gold coins.