Cairn House
The Cairn House is the largest prison in the region, built to hold criminals, war captives, dangerous monsters, and one creature no ordinary jail could contain. The visible prison occupies a broad hilltop compound enclosed by high walls and watchtowers. Beneath it lies a second prison of sealed galleries, isolation cells, laboratories, armories, and warding chambers. At the deepest point rests the Red Pit, where a living tarrasque is held in enchanted stasis. The facility is designed for a party of 5th-level adventurers to explore through negotiation, infiltration, rescue, investigation, or a desperate attempt to prevent a containment failure.
Cairn House
Orderly, quiet, and unnervingly clean. The air smells of limewash, lamp oil, boiled grain, and cold metal. Guards speak in low voices, prisoners shuffle under constant supervision, and distant bells divide the day into measured pieces. Near the lowest levels, the walls tremble once every few minutes with the tarrasque's slow breathing.
The Cairn House is the largest prison in the region, built to hold criminals, war captives, dangerous monsters, and one creature no ordinary jail could contain. The visible prison occupies a broad hilltop compound enclosed by high walls and watchtowers. Beneath it lies a second prison of sealed galleries, isolation cells, laboratories, armories, and warding chambers. At the deepest point rests the Red Pit, where a living tarrasque is held in enchanted stasis. The facility is designed for a party of 5th-level adventurers to explore through negotiation, infiltration, rescue, investigation, or a desperate attempt to prevent a containment failure.
Patient, formal, and politically cautious. She treats the prison as a public trust rather than a personal holding, but her caution can become paralysis when decisive action is needed.
History
Security Measures
The prison uses six overlapping security systems. The outer wall is built from pale granite blocks sunk into a moat of packed clay and gravel, with no drawbridge or visible gatehouse door. Entry is through a sloping tunnel that can be sealed by three stone plugs. Inside, wardens carry iron keys marked by shape rather than teeth, allowing each key to open only one class of lock. Every corridor contains murder holes, signal bells, and narrow inspection shutters. Spellcasters maintain permanent wards against teleportation, ethereal travel, planar escape, and unauthorized summoning. The wards are strongest near the lowest vaults, where the tarrasque is held. Prisoners are searched by hand, magecraft, and trained hounds before entering the main block.
The Red Pit
The lowest chamber is called the Red Pit, named for the iron-rich stone exposed beneath its floor. It is a vast circular vault sunk below the prison, large enough to contain a crouching tarrasque. The beast is not held by chains. Instead, twelve anchor towers project bands of force that pin its limbs and jaw whenever it wakes. Each tower is powered by a crystal housed in a separate guarded room, and all twelve must remain active. The chamber has a reinforced ceiling, layered ventilation shafts, and a feeding chute large enough for an ox cart. The floor is covered in replaceable slabs over a bed of shock-absorbing sand. The prison staff insist that the tarrasque sleeps, but its breathing still makes dust fall from the ceiling.
Notable Prisoners
Most prisoners are political captives, dangerous spellcasters, condemned raiders, and creatures too valuable or destructive to execute. The best-known inmate is Hesh of the Salt Road, a hobgoblin war captain who surrendered rather than lead his soldiers into a massacre. Sava Oru, a human diviner, is kept in a room whose walls are coated in wax to prevent her from reading vibrations through the stone. Brother Teth, an elderly dwarf relic thief, has become an unofficial adviser to new inmates and knows three forgotten routes through the service passages. None of them is held in the tarrasque wing, but each has heard something about the creature's dreams.
Daily Operation
The prison employs strict routines to prevent panic. Bells mark meals, inspections, work details, and the changing of watch. Prisoners receive clean water, decent food, medical treatment, and limited access to a sunlit exercise yard. Violent inmates are separated by temperament rather than social rank. Wardens are forbidden to use torture, both by law and because fear is believed to make the tarrasque more restless. Visitors may speak with prisoners through grated interview rooms, but every conversation is observed by a clerk behind a one-way glass screen.
Denizens
Patient, formal, and politically cautious. She treats the prison as a public trust rather than a personal holding, but her caution can become paralysis when decisive action is needed.
A human woman who commands the prison with strict fairness. She refuses bribes, dislikes cruelty, and believes the tarrasque can be contained only while the staff remain disciplined. She secretly keeps a written succession plan in case the lower vault fails.
A broad-shouldered dwarf engineer with soot-dark hands and a talent for repairing magical machinery. He has noticed that one anchor crystal is losing strength, but fears reporting it will cause the crown to send reckless investigators.
A soft-spoken elven clerk who records every prisoner movement and guard change. She appears timid, but has memorized the entire prison layout and knows that several old passages do not appear on official plans.
A hobgoblin prisoner and former battlefield commander. Hesh is calm, observant, and respected by inmates who value practical advice. He claims the tarrasque is not asleep but listening.
A human diviner held in a wax-lined cell. Sava has foreseen a night when the Red Pit opens, but she cannot tell whether the disaster will be caused by sabotage, accident, or the tarrasque itself.
An elderly dwarf thief who stole relics from sealed tombs. Brother Teth acts as a caretaker for weaker prisoners and knows where the old quarry tunnels meet the modern foundations.
Rumors & Plot Hooks
- 1.The tarrasque has learned the names of every guard assigned to the lower levels.
- 2.One anchor crystal has been replaced with a convincing glass imitation.
- 3.A forgotten quarry tunnel opens behind the Red Pit and leads beneath the surrounding countryside.
- 4.The prison's founders built a second containment chamber below the first, and the tarrasque is not the only thing held there.
- 5.A prisoner who dreams near the lower vault sometimes wakes with fresh claw marks on the inside of their cell door.
- 6.The royal court intends to move the tarrasque, despite having no vessel or escort capable of surviving the journey.
Classified Entry
The tarrasque is not being held only as a threat. The royal court has discovered that its shed scales can be ground into a substance that strengthens protective wards. For years, wardens have secretly collected pieces from the Red Pit and sent them to court arcanists. The creature's increasing agitation is caused by these harvests, and the failing anchor crystal is the first visible sign that the arrangement cannot continue. If the party learns the truth, they must choose whether to preserve the prison, expose the court, free the tarrasque, or find a way to end the exploitation without unleashing a catastrophe.
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