The Thing In The Septic Tank

An introductory scenario drawing inspiration & influence from Amazon’s Bosch series.
Pregens can be found in STAT BLOCKS; by the end of the scenario they may become Delta Green Agents.

This scenario can be played three ways:
CONVENTION STYLE with an In Media Res opening as Mitchell escapes from FIELD TRIP
LONGFORM with the routine traffic stop of Mitchell’s van, allowing players to feel out & introduce each other narratively (Recommended for new players)
STANDARD with Delta Green Agents instead of LVPD Officers after FIELD TRIP


Six months ago, an object penetrated the Earth’s atmosphere & landed in the desert outside of Las Vegas, Nevada. It was a biological life-raft for a dying god, Baoht Z'uqqa-mogg, fleeing Shagghai millennia ago. Left weak by the journey/impact, it sounded a hypersonic cry for help, heard around the world by Shan.

Before they could arrive, a hiker, Reginald Mitchell, found the scorpion-like creature & nursed it with field mice & other critters. Its insatiable hunger & rapid metabolic growth caused it to hunger for larger food.

BZM endowed Mitchell with new powers for his help. Over six months, Mitchell abducted humans & took them to BZM’s lair where it hunted for sport. After devouring & absorbing them, Mitchell took the bones, packed them into duffel bags, & buried them to ritualistically & ceremonially point to Shagghai to channel more powers.

LONGFORM: Mitchell is in custody on the side of the road after a traffic stop. He is suffering an Anxiety attack. Officer Pollux saved a kidnapping victim from Mitchell’s van. All Agents are present at the side of the road.

After finding himself in custody & realizing that he can’t dig through the county’s concrete floor, he schemes in his dreams with three Shan-infected companions to make an escape plan. He makes a plan with Shan-infected companions (Shanigans) in his dreams. He plans to break free by making a plea deal to go on FIELD TRIP: no death penalty & he’ll lead police to the bodies.

CONVENTION STYLE: The traffic stop has already happened, as well as the deal. FIELD TRIP is underway. Three Shanigans lay in wait, ready to spring Mitchell, in service to BZM.



You agreed to a “field trip” where Reginald Mitchell, the suspect in a string of kidnappings, will lead you to where he has allegedly buried four kidnapping & homicide victims over the course of the last few months. Mitchell says that they are all buried by the Las Vegas Bay Campground.

District Attorney thinks this is the best way to get everyone what they want: a solid conviction, closure to the family, & appeasement to the public that the police can still keep them safe. The death penalty doesn’t matter when this monster will be locked up for 5 life sentences


The Las Vegas Bay hiking trail is where Mitchell & Shanigans plan his escape..


  • Mitchell uses his strength to break through the handcuffs when the opportunity presents itself.
  • Shanigans are posing as British tourists. Strategies may include:
    • Distracting the police with curious questions
    • Misleading the police
    • Pulling up with a getaway vehicle
    • Picking up Mitchell in a motorboat down the waterway.


As Agents chase Mitchell, they can leverage the NVPD for help.

Official Requisition rolls are at +20% due to the high profile case.

  • Squad of Patrol Officers (Standard Expense): the fastest response time, these guys are looking for some action & credit in nailing this guy (again). A mix of rookies & veteran cops.
  • SWAT (Unusual Expense): useful for armed, barricaded, or tactical situations.
  • AIR ONE: (Major Expense) helicopter equipped with FLIR heat-cameras & other person-detecting measures

If Agents squander resources, they trigger Official Review.


All are initially encountered by Mitchell while working, a common trait. Also have residences close to underground entrances.

Dead Victims
NOTE: bone burial sites are marked on Handler map

  1. Carly Winnefield
  2. David Dismukes
  3. Margo Nott
  4. Niesha Webb

Living Victim, Joaquin Rodriguez, is saved from the van by Office Pollux. Rodriguez has not been thoroughly debriefed, & is currently at the hospital undergoing surgery for bones broken by Mitchell. If he is questioned, he offers utterances & behaviors by Mitchell during his time as a victim that may point to entrances to the underground.


Mitchell was a water drainage specialist contractor, repairing & installing drainage & septic tanks.

  • Cell phone
    • Reveals locations, hiking trailhead check-ins
    • Mitchell is not particularly bright, nor is he insidious. On his days off, he enjoys hiking trips & maintains an online record of his trips on Instagram & a personal blog, complete with photos & videos. About six months ago, he started urban exploration into drain pipes & Vegas’ sewer system.
    • Art:
      • Sketches: Planet with a red eye eating another planet, labeled Groth & Shaggai.
      • A shrine: dead bugs pulled apart & crazy-glued together in BZM’s likeness
  • Van
    • Forensics confirms that the five victims were at one point in the van via DNA evidence.
    • Science or Forensics matches the van’s & Mitchell’s hiking boots to Las Vegas Bay Campground.
    • Work site logbook. Cross referenced with dead victims’ addresses & potentially reveal new targets (asterisked*)
  • Residence
    • Mitchell’s house is an odd labyrinth constructed of dirt & human spit, moving throughout the house requires crawling through these cramped tunnels, or else destroying them (making a 20% penalty to tests to look for things)
    • Maps of underground tunnels with hand-drawn additions of diggings he’s made
    • Drawings/sketches of scorpions & winged beetles
  • Tourist’s hotel
    • Staff tells a weird story about all three tourists stopping & turning their heads sideways, as if listening to something at the same time
    • Room is completely dark, with extra curtains & tape used to black out windows
    • Shan excrement makes the floor sticky, visible with blacklight
  • Rodriguez’s residence
    • Entrance to underground tunnel can be found by septic tank


Sociopathic aliens piloting humans like mechs, the Shan have poor understanding of human society.
Shenanigans are attempting to understand and navigate the human world while serving higher powers.

Taking a Shanigan into custody, they will explain their situation, trusting their understanding of human laws to keep them safe while looking for a more powerful form.

Traditionally, Shan worship Azathoth, but these rebels see an opportunity to elevate BZM back to godhood now.


Baoht Z'uqqa-mogg is a large, powerful winged scorpion-like monstrosity with an ant-like head. BZM once inhabited the now-dead planet of Shaggai, destroyed by the god Ghroth. BZM escaped in a pod & was stuck in a torpor before crash-landing on Earth.

BZM is an enormous arachnid/scorpion being: huge compound eyes, myriad antennae, ant-like mandibles dripping highly toxic saliva, & a pair of expansive, leathery wings.

It can often be found surrounded by its young, a swarm of flying insects that have a venomous sting.

It can bestow abilities to its followers, & will reach out to PCs in their dreams in an attempt to recruit them.

BZM’s influence leaks into the dreams of Agents.

  • Cryptic art in human blood & other unknown matter, of coyotes digging, pigeons circling and the buzz of insects
  • Being chased down a dank hallway, never seeing what is chasing them but hearing the rapid taps of many legs & dripping water

Agents awaken with quickened heartbeats & anxious feelings of being very tiny. A 0/1d4 SAN test, the same amount gained in Unnatural.

They’ve been offered a choice: to serve or not.

Rejecting means being plagued by insects constantly.

Accepting means being granted a boon (roll 1d6 or choose), with a 1d8 SAN loss (and the same amount gained in Unnatural).

They also feel a compulsion towards BZM, as well as the need to bring it food & actions that would harm BZM costs 1d4 SAN and WP.



Cramped & claustrophobic storm drains, natural tunnels/caves & the Las Vegas Aqueduct form a labyrinth.

Entrances are wherever is narratively convenient, taking hours to travel through. Using Mitchell’s map grants +20% to movement.

Cell/Radio signal is spotty at best.

Navigating is a skill challenge with a 4-segment success clock.

Failures mean a chance to react before the bad thing happens; Fumbles mean it happens immediately.

  • Ambushed by Shanigans
  • Walking into a trap set by Mitchell
  • Falling & getting hurt
  • Losing vital equipment
  • Bond calls at a bad time

Filling the clock means finding BZM’s lair, a larger chamber marked by rancid spittle.


Shortly after/during the confrontation in BZM’s lair, Agents’ cell phones buzz/ring loudly warning of a flash flood
They’ll be swept away if they don’t leave, (use the same clock as above) but could survive with Swim or Athletics (20% penalty).


Agents are accountable for

  • Dead bodies (civilians & police)
  • Weapons fired
  • Resources Used

Survivors are approached & recruited by Delta Green.


1d4 for defeating BZM and confirming the kill.
1d4 for stopping Mitchell



pregens folder

To be taken by players in this order
Brugel, Pollux, Sheehan, Marren, Schiff, Mabe

Any PCs not played will be used as NPCs to be directed or utilized by PCs during the investigation.

Players can assign stats, change gender, sexual orientation, & even reallocate skills as they see fit.

Some Bonds are mandatory, but others are merely suggested.



The Bringer of Pestilence
STR 41 CON 41 DEX 11 INT 15 POW 21 HP 41 WP 21
ARMOR: 5 points of Chitin, and RESILIENT
SKILLS: Alertness 40% (see TREMORSENSE), Athletics 60%, Flight 30% (see LIMITED FLIGHT), Stealth 70%
Stinger 40% damage 1d2 with 5AP, 20% Lethality poison w/ speed 1d6 hours
Claw 50%, Damage 1d6 with 5AP, a critical success means the target is pinned.
AMBUSH TACTICS: Baoht Z'uqqa-mogg prefers to hunt from stealth, hiding under surfaces and striking at opportune moments.
CAMOUFLAGE: When sitting completely still, Baoht Z'uqqa-mogg imposes a 40% penalty to checks to see it with the naked human eye. Other modes of vision can aid in detecting it, such as night vision, heat vision, or ultraviolet light.
COMPRESSION: Baoht Z'uqqa-mogg can compress themselves into spaces that might seem impossible.
LIMITED FLIGHT: Baoht Z'uqqa-mogg flaps insect wings and can fly low to the ground (no more than 30m high). This does not work if its wings are wet.
FEEDING: If Baoht Z'uqqa-mogg has given birth, it will capture targets (alive, preferably) and bring them back to its lair to train its young in the ways of hunting
TREMORSENSE: Baoht Z'uqqa-mogg can detect beings that it cannot see by their footsteps and other auditory clues up to 800m away. The range for this ability is increased underground, and it doubles its Alertness score when hunting). This may be overloaded by cacophony or tricked by walking without rhythm.
UV VULNERABILITY: Ultraviolet light is hostile to Baoht Z'uqqa-mogg, and can be used to track it via its fluids. Direct sunlight both damages it and blinds it (a 40% penalty to attacks and skill checks made in sunlight).
RESILIENT: A successful Lethality roll does not destroy Baoht Z'uqqa-mogg, but inflicts HP damage equal to the Lethality rating.
VENOM: Baoht Z'uqqa-mogg’s stinger contains fast-acting venom (1d6 hours, rolled in secret by the Handler). If the 20% Lethality roll fails, the victim makes a CON×5 test to withstand harm. Success means half damage, and a critical success means the victim loses only 1 HP. A fumble doubles the damage. Hospitalization grants +20% to the victim’s CON test.
To more easily track poison, make a progress clock with a number of segments equal to the 1d6 hours’ speed (0-6 segments). A 0 means death.

Other symptoms of the poisoning:

  • double vision, breathing difficulties.
  • muscle thrashing or twitching
  • unusual movements of the neck, head, and eyes.
  • dribbling or drooling
  • Sweating
  • Nausea
  • Vomiting
  • high blood pressure

SAN LOSS: 1d4/1d10


STR 3, CON 3, DEX 15 HP 18
Swarms of insects do 1d2 damage per turn every turn in a 1m cloud.
On odd numbers, it also poisons the agents (as Baoht Z’uagga-Mogg’s VENOM ability) but with an initial CON x 5 roll to save against being poisoned.
This ignores armor, as the insects find exposed areas.
Reducing the swarm to 0 HP kills enough of the bugs to drive the rest off.


STR 24 CON 24 DEX 15 INT 12 POW 13 CHA 7 SAN 21 BP 15
DISORDERS: Adapted to Violence, Anxiety, Fugue States
SKILLS: Alertness 70%, Athletics 85%, Stealth 90%, Unarmed Combat 50% Unnatural 20%.
ATTACKS: LIFT AND THROW 50%, damage varies (minimum 1d6, ignores armor except helmet)
LIFT AND THROW: With a successful Pin, Mitchell can choose to throw/slam the victim for damage. Mitchell can Pin two people at once.
BURROWING: Mitchell can burrow through earth at up to three meters per minute.
INHUMAN AGILITY: With a successful Athletics roll, Mitchell can leap five meters in any direction from a standing position, scale any vertical surface, or drop up to 15 meters without damage. At top speed, Mitchell can run nearly 60 kph.
COMPRESSION: Mitchell can fit into places that seem impossible for regular humans, including drainage catch basins and sewer pipes.
EXOSKELETON: Chitin provides 5 points of armor
RESILIENT: A successful Lethality roll does not destroy Mitchell, but inflicts HP damage equal to the Lethality rating.
Speaking Dream

If he has claimed another victim, give him
FLIGHT: Mitchell has developed insect wings capable of rudimentary flight.
STINGER: Mitchell grows a scorpion tail from his derriere, with an attack of 40% and Lethality 10% poison (use the same VENOM as in BZM’s stat block). It costs 1 HP to use this as an attack.

SAN LOSS: 1/1d4 when his true forms are revealed


Name Generator
Three out of place British tourists.
STR 10 CON 10 DEX 10 INT 10 POW 10 CHA 7 HP 10 WP 10
SKILLS: Alertness 50%, Athletics 50%, Melee Weapons 50%, Stealth 50%, Unarmed Combat 50%
ATTACKS: Big knife 50% (1d6 w/ 3 AP), Club 50% (1d6), Punch 50% (1d4-1)
SHAN INFECTED: If the Shanigan die in sunlight, the Shan linger inside awaiting the autopsy, at which point they will attempt to take over new hosts

Insect From Shaggai

STR 1 CON 3 DEX 22 INT 23 POW 20 HP 2 WP 20
SKILLS: Alertness 99%, Dodge 93%, Flight 50%, Unnatural 60%.
ATTACKS: Bite 40%, damage 1D4.
OUT OF PHASE: The insects from Shaggai exist in a multitude of dimensions. If a damage roll or Lethality roll is an odd number, the insect has shifted out of phase with our dimension and is immune to the attack.
POSSESSION: On a successful Flight skill roll—and a failed Dodge roll on the part of the target—the insect can enter the target’s brain. If this happens, the target may attempt a single POW test to struggle free of the insect’s control. If it fails, the target loses all WP and becomes the insect’s puppet, under its complete control for 1D6 weeks.
The target remains conscious of any deprivations committed under the insect’s influence in that time, and loses SAN accordingly. Piercing the skull while an insect is inside (treat this as any head wound that inflicts at least 3 HP damage on the target) forces the insect from the target. Deliberate trepanation requires a Medicine roll. Success or critical success inflicts exactly 3 damage; failure inflicts 1D6+2 damage, doubled on a fumble.
NON-TERRENE: The insects are at home in nearly any environment. Radiation, pressure, cold, vacuum and other inimical environments have no negative effects on them.
SUNLIGHT: Sunlight is poisonous to the insects from Shaggai. Exposure to it inflicts 1 HP damage per turn.
AETHERIC FLIGHT: The insects “fly” on some invisible aether, allowing them to move with wings even in space. On Earth, this means they can fly up to nearly 40 kph.


This was an entry to the 2020 Delta Green shotgun scenario contest, written by Jake "Chief McClane" Cook

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