The Haunted House
This scenario has been published in editions of Call of Cthulhu since the game first appeared in 1981. I'm outlining it here to use its very familiarity to illustrate the distinctive features of Cthulhu Abides.
PCs are asked to investigate the haunting of the Corbitt House in Boston (I prefer Boston in Lincolnshire). The landlord, keen to rent out the property, gives the PCs the keys and a small cash advance.
Questioning the landlord can involve roleplaying or Charm/Investigate Challenges. Success earns a Testimony Clue Point and information about the previous tenants, Russian emigres who lived there for a year before both mother and father went insane after the father's serious accident.
Mr and Mrs Makariy are in a nearby asylum - either Kesteven County Asylum or the Lincolnshire County Lunatic Asylum. Doctors and others who have the place as a Archive may access it freely; other characters must make a difficulty 10 Access Challenge. Viktor offers no help but his deranged condition may be Disturbing to study. Gavriil recalls the evil presence in the house and details of poltergeist phenomenon. This is worth a Testimony Clue and is a Disturbing Idea.
The Makariy children are being cared for in the Boston Union Workhouse. Their Testimony Clue repeats their mother's dreams of a strange man with burning eyes.
Journalists may access the Boston Standard as an Archive but others must make an Access Challenge. Up to two more Testimony Clues can be gathered here from news cuttings about earlier tenants (poor immigrants) who fell prey to accidents and madness back as far as a fire in 1878.
Accessing Boston Library will reveal Evidence Clues, such as Walter Corbitt buying the house in 1835 but being forced to leave by his disgusted neighbours. Spending a Clue turns up the legal papers, showing Corbitt resident in the house again until his death in 1866 and a lawsuit to prevent him from being buried in the basement.
Detectives may study police records but other characters must makes Access Challenges. An Evidence Clue links Corbitt to Rev. Michael Thomas, minister at the Chapel of Contemplation, which was closed in 1912. Spending 1 Clue produces the revelation that the authorities raided the chapel after the disappearance of local children: several police officers and congregationists were killed in the raid.
The Chapel of Contemplation itself is an Elder Ruin. Exploring the ruin can yield an Evidence Clue Point, a point of Insight, 1D Sympathy and a damaged translation of the Liver Ivonis (-1D Potency, -1 Limit on all rolls) will be found if all 4 Danger Checks are attempted. Security is an unsafe floor and a fall into the basement that delivers a Stunning Wound (no Dodge or Fall Resist allowed).
PCs who are members of a Mythos Cult may access it to learn that the Chapel of Contemplation was an offshoot of the Starry Wisdom Cult. If anyone can access the Starry Wisdom Cult itself (!), they will hear of Corbitt as a renowned sorcerer in his day who achieved the secret of immortality. Gnosis gain from infiltrating the Cult could be used to create a Spell to destroy Corbitt.
If the characters go to the Corbitt House to soon, they won't have the Clue Points to get into the hidden basement tomb.
The Old Corbitt Place
Entering the house is a Threshold Crossing and costs a single Clue Point. There is a Sense of Danger Stressor within. In the downstairs rooms, Corbitt's diaries are Epistles worth 3 Mythos Insight and 1D Azathoth/R'lyeh Incantation (double if used against Corbitt) but offer Unnatural Shocks. Anyone noticing the preponderance of Russian Orthodox religious Art can gain an Evidence Clue or Esoteric Insight.
Upstairs, Corbitt's Geist activities focus on the second bedroom, where all sorts of Perils can emanate. Profound or Unnatural Shocks may be caused by strange sounds or moving furniture or PCs may have to resist difficulty 9X Stunning attacks (physical or magical) using only Maim/Geist and Trauma.
The basement has another Peril in the form of an unsafe stairwell (difficulty 8 Stunning attack, resist with Maim/Fall). Another Geist Peril here is Corbitt's sacrificial dagger which can float and attack: this is Unnatural as well as as a difficulty 9X Magical Killing Wound. If the dagger can be captured it is a 1D Mythos Athame (2D against Corbitt).
Breaking through the wall space into Corbitt's secret tomb is another Threshold Crossing. Spending 5 Clues allows a safe crossing, otherwise the rats in the wall attack. This is a Profound Shock and a difficulty 10 Stunning Wound that cannot be Dodged or Fallen in the narrow space.
The Ordeal - Defeating Corbitt
When Corbitt's body rises to defend his lair (an Unnatural Stressor), treat him as a weak Mythos Mummy with 12X Magic, Resistance & Enmity, Attack/Defend 10 and Damage 9. He has three main magical powers: Binding 15X lets him control the mind of someone within the house, normally driving them mad (Mythos Stressor) or making them hurt themselves; Curse 9X uses telekinesis to attack people; Ward 7X must be magically resisted before normal weapons will harm him.
Clue Points can be used as Bonuses in fighting Corbitt. PCs might use magic against him, such as a Mythos Curse to turn him to dust. Corbitt's Diary counts as a 2D Incantation and the Chapel of Contemplation is worth 1D Sympathy and the knife is a 2D Athame when used against Corbitt. If the Spell is successful, the Potency must beat Corbitt's 12X Enmity. The Liver Ivonis will help here - it has 14D Potency even in its ruined state but the -1 Limit from its damaged state and Corbitt's 12X Enmity means the overall Potency roll has a -2 Limit and needs difficulty 12 to destroy him. The GM might allow Esoteric Magic to work but this will only Stun Corbitt, making him collapse and appear truly dead although he will later rise again unless the body is burned.
There's no cost to return to safety afterwards. The gem around Corbitt's neck is a Mythos Athame that deducts 1D from the difficulty of Azathoth/R'lyeh spells.
This scenario was published back in 1999 on Stephen Hatherley's Tales of Terror site. I've reprinted it here with adaptations for Cthulhu Abides.
Someone close to the investigators is succumbing to a horrific disease. Symptoms include unpredictable attacks of agony; loathsome swellings, horrible alterations in skin texture and bone structure, and foul excrescences. Conventional doctors are mystified and alternative therapies are futile - because the sufferer is turning into a ghoul.
Oddly, a group of stalkers seem interested in the invalid, following him everywhere and breaking into the offices of some of his doctors to steal case-notes. If observed, they too are suffering from a disfiguring disease.
As the character becomes increasingly debilitated, his friends (the investigators) discover Dr Ladislav’s Sanatorium. Ladislav is a gaunt cadaver of a man who greets his new patient with strange excitement. The patient has a private dorm with every luxury during his stay but the doctor will not discuss his radical therapy and is very anxious for his friends to leave. These characters notice a larger wing of the Sanatorium which more closely resembles a high-security prison (yes, Ladislav explains, the Sanatorium was once a gaol last century). Orderlies leaving the Old Wing have blood on their uniforms.
And that is the last they hear of their friend. Mail isn’t answered nor are calls returned. The stalkers ransack the sick character’s old residence and will be seen lurking near the Sanatorium. If the investigators return to the Sanatorium, Dr Ladislav, looking disturbingly decayed, has no records of the patient’s admission and the luxury dorm is occupied by an elderly man with gallstones.
1 Ladislav heads a necrophagic ghoul-cult, and the Old Wing’s cellars access nearby ghoul warrens. Patients are treated with foul transfusions and rituals until they transform fully; others are eaten. All food served at the Sanatorium is human flesh, either that of patients (their extremities surgically removed over a period of time to grace the Doctor’s table) or from corpses from the old gaol cemetery.
The ‘stalkers’ are a group of patients who escaped through the ghouls’ tunnels: half-demented and hideous, they are desperate to rescue fellow-sufferers from the Doctor, but are in terror of ‘regular’ humans and ghouls alike. The sick character is in the last stages of transformation, but may be saved in the nick of time. A long-term cure is still needed...
2 Ladislav is a Mythos scholar dedicated to finding a ‘cure’ for ghoul-ishness. His treatment is exceptionally brutal, involving electrocution, organ transplant with hallucinogens instead of anaesthetic and physical purgings. Obviously, he would be incarcerated if his therapeutic methods were known.
The ‘stalkers’ are true ghouls, looking to liberate their half-changed brethren from the good doctor’s clutches. They are hideous, but oddly sympathetic - compared to Ladislav, anyway. The ghouls would like to destroy the Sanatorium and rescue the inmates, but aren't sure how.
3 Ladislav is himself becoming a ghoul. His treatments are all attempts to stave off his own inevitable transformation: he used to transplant fully-human organs into himself, but his ghoulish body has started rejecting them. Now he needs partial-ghouls for transplant subjects, victims less far gone than himself.
The ‘stalkers’ are Ladislav’s former-patients, too far gone into ghoul-ishness to be useful transplant subjects (though they bear the amputations of earlier surgeries). Instead, they now locate fresh victims for the Doctor in the (futile) hope that, once he is cured, he will in turn cure them. They’re a pitiful crew, but may be turned against the one who did this to them by a investigator sensitive to their tragedy.
Doctors or anyone with First Aid may make Intellect/Profession Challenges to examine the sufferer. The difficulty is 10 and success produces a Profound Shock and either an Evidence Clue or Insight, depending on the medic's Madness Level. Taking tissue to examine counts as acquiring a one-shot Mythos Grimoire (Difficulty 10, Unnatural Shock, 2D Potency, Hyborian/Azathoh) but the Investigator gains a Ghoul Point from this sort of research. Any players figuring out that ghoulishness is to blame may gain a Deduction Point.
This is a great opportunity for Perils. Encounters face-to-face with the monstrous stalkers are Profound Shocks, but other Perils may be Dangers (finding yourself followed or ransacked) or Disturbing Ideas (glimpses of the stalkers).
Investigators may turn to Grimoires, Archives and Elder Ruins (graveyards) and infiltrate the Culte des Goules. They will discover their friend had been spending time in a local graveyard, mausoleum or necropolis - perhaps seeking artistic inspiration, pining for a loss or investigating history, cadavers or the occult.
Spending a Clue Point turns up the name of Dr Ladislav, an expert in medical cases like this.
Players should be discouraged from crossing the Threshold too early so set the crossing fee high if they want to go sneaking around the sanatorium - 8 Clue Points should do it. Charge Clue Points to notice details like the bloodstained orderlies or to learn about the sanitarium's former function as a gaol.
Players can gain the necessary Clue Points from the break-ins and by pursuing the mysterious stalkers, who always melt away. Even finding mail unanswered is worth Clue Points as is noticing the change in Ladislav and researching his background (see below for ideas). When the players have 8 Clue Points, they can return to the sanatorium and cross the Threshold into danger.
Investigators may break into the sanatorium or pursue the stalkers. Discovering the true nature of the experiments will be a Profound Shock as will be meeting with the semi-Ghouls. 5 Clue Points will "buy" the semi-Ghouls as allies but the GM may allow players to roleplay persuasive arguments or make Charm/Occult Challenges (difficulty 10, minus 1 for each Clue Point spent).
Ladislav should be treated as a Deranged Magician with Evoking Magic that can only be used to turn people into Ghouls; curing Ghoul Points is a Potency 15 effect currently beyond Ladislav's power (unless he is assisted by a Grimoire of some sort).
In options 1 & 3, Ladislav's orderlies are Maniac Cultists and there are Ghoul allies that will defend him. In option 2, the orderlies are Secondary Characters and the Ghouls will attack the sanatorium, with the players forced to take a side.