Gamemaster’s Guidepost: The Plague City

Guest Post by S. A. Fisher

Most people fled from cities infected with the bubonic plague. For instance, Giovanni Boccaccio’s The Decameron revolves around the storytelling of survivors who fled Florence, Italy during its plague years. Player characters, however, may have business inside a plague city. How do you handle that? Mashup GURPS Bio-Tech and GURPS Zombies, of course.

Why a Plague City?

There are several reasons why adventurers might be inside a plague city:

  1. Loot: With so many dead, and so many fleeing, the promise of unprotected treasures is mighty enticing.
  2. Rescue: The heroes may enter the plague city to rescue a relative, a love interest, or an ally or patron.
  3. Pilgrimage: Characters may want to visit a specific temple or church to pray to a specific god or saint, retrieve holy water from a specific font, or retrieve a specific book, icon, or relic.
  4. Murder: The PCs may take advantage of the chaos to even a score, taking out a sworn enemy or carrying out a contract for a patron.
  5. Research: The city may contain a library where the heroes have some interest.
  6. Escape: Rather than entering the city on a specific mission, the heroes may be locked inside a villa under quarantine and now must flee the plague city. After 40 days they are out of supplies and must escape.

Bubonic Plague

The “Black Death,” caused by the bacterium Yersinia pestis, devastated Europe in the Middle Ages. Bubonic plague is typically spread by rat-borne fleas and affects the lymph nodes; this most common form of the plague is fatal in 55% of cases if untreated. Bubonic plague may progress to septicemic plague, which is an infection of the blood, or infect the lungs and become pneumonic plague, which can spread via respiratory droplets. Untreated, septicemic and pneumonic plague are 100% fatal.

Early symptoms of the black death are shivering, headache, vomiting, and high fever. As the body temperature rises, the victim becomes sleepless, apathetic, or delirious. The most characteristic sign of bubonic plague is black or purple swollen lymph nodes in the armpits and groin, called buboes. Roll Diagnosis+2 on first sight of a victim with buboes to determine the cause.

Each day a person is exposed to bubonic plague, roll against HT-2 (but see equipment bonuses below, and Contagion in Basic Set, p.443). A critical success means the character is immune to the plague and no longer needs to make daily health checks. A failure means the character has contracted the plague; a critical failure indicates a case of pneumonic plague (see below). An infected victim will fall sick in 1d6+1 days. Once infected, roll against HT-2. Success means the disease has been defeated and the character can now recover. If the HT-2 roll fails, the character takes 1d-2 toxic damage. Repeat this process for twelve cycles at six hours each! The first symptoms (fever, headache, etc.) appear after the subject starts to suffer injury. Symptoms produce severe pain (p. B428) and Unnatural Features 1 (buboes) after the loss of 1/3 HP.

Pneumonic plague is spread by respiratory droplets, not flea bites. Roll versus HT-6 to resist contracting pneumonic plague, with a 1d/2+1 day delay. If infected, the victim takes 1d toxic damage for each 12-hour cycle. Roll versus HT-6 or repeat for a total of 12 cycles. Symptoms include moderate pain and coughing (p. B428) after the loss of 1/3 HP. After the loss of all HP, the victim suffers from Choking (p. B428) and then dies.

Septicemic plague is spread via flea bites when the bacterium Yersinia pestis infects the victim’s blood. Roll versus HT-6 to resist contracting septicemic plague, with a 1d/2-1 day delay. If infected, the victim takes 1d+1 toxic damage for each 6-hour cycle. Roll versus HT-6 or repeat for a total of 12 cycles. Symptoms produce severe pain (p. B428) and Unnatural Features 1 (black, necrotic extremities) after the loss of 1/3 HP. After the loss of 1/3 HP, the victim suffers from Hemophilia, with bloody vomiting and diarrhea (treat as Retching p. B428). After the loss of all HP, the victim suffers from Choking (p. B428) and then dies.


The rules above assume normal exposure without protective efforts. Roll versus HT daily when in a contaminated plague city. GURPS Zombies provides especially helpful rules for plague exposure: see Biohazard, p.119 and Splatter, p. 125.

Handling infected plague bodies or corpses always has risks attached. This requires a Hazardous Materials (Biological) roll, with success indicating no special exposure that day. Failure means an extra roll to resist is needed, although precautions still help. Critical failure signifies a serious exposure, such as a jagged bone from a corpse piercing the skin, or a bit of grue splattering the face — roll to resist immediately at -3, with no bonuses for precautions.

Treatments and Health Aids

Insect Repellent: Herbs can help repel disease-carrying fleas. Oils and essences from rosemary, thyme, mint, lavender, and citronella are effective, giving a +3 to HT to avoid the plague from fleas.

Protective Armor and Clothing: waterproof clothing, and any armor with DR 1+, gives +2 to HT rolls for contagion if the whole body is covered, including the face. Leather eyeglasses, like 1920s motorist goggles, can be fashioned to cover the eyes and gives a +1. The +3 to HT rolls only apply if the whole body is protected! The iconic plague doctor mask of the 17th century, with goggles and beaked face mask (stuffed with herbs or vinegar-soaked sponges), and leather cloak and gloves would provide full +3 to HT protection.

Four Thieves Vinegar: One treatment known as the “four thieves’ vinegar,” mixed angelica, camphor, cloves, garlic, marjoram, meadowsweet, wormwood, and sage, all brewed in vinegar. This was used to wash hands and bathe. The name is derived from the legend that four thieves stole from the homes of dead victims and protected themselves with the vinegar solution. Vinegar was used as a disinfectant on the skin. Wine was also used, with the same effects. Garlic and the other spices and herbs do have some antimicrobial and insect-repelling properties. Effect: +1 to HT rolls.

Herbal Baths: Some physicians recommended taking lavender or rosewater baths for protection or treatment of the plague, which probably did help due to their antimicrobial and healing properties. Effect: +1 to HT rolls.

Willow Bark: Physicians recommended taking willow bark tea as a plague treatment. Willow bark tea is an effective painkiller and fever reducer. It acts as a natural analgesic, anti-inflammatory, and fever reducer. Effect: +1 to HT rolls.

Cleaners and Clean Water: Myths about the “unwashed middle ages” aside, soap and clean water were commonly used for washing up. Lye soap was a common homemade soap, though more expensive olive oil soaps could be had. Effect: +1 to HT rolls.

If the adventurers take all available precautions the maximum effect is +6 to daily HT rolls against exposure. If they fall victim to the plague, the herbal teas and baths may provide up to a +2 to HT rolls to recover.


The plague zone is a high-drama location for roleplaying scenarios. Exposure to disease is a constant threat, and any contact with a live person or a corpse increases the chance of infection. Combat with plague-infected enemies is to be avoided, and so this flips the script. Stealth and avoidance are the key survival traits. This smacks of a zombie apocalypse, and for good reason. The plague years are one of the cultural memory stores from which the modern zombie apocalypse was born.


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