Running classic TSR modules like L2: The Assassin’s Knot (Len Lakofka, 1983) and B6: The Veiled Society (David "Zeb" Cook, 1984) using the Castles & Crusades (C&C) system is an exceptional pairing.
Because Castles & Crusades uses the Siege Engine mechanics but explicitly retains the math, tone, and architecture of Early Edition D&D (specifically AD&D 1e and Basic/Expert), these modules require virtually zero stat-block conversion. However, since both of these modules are pioneering urban investigation adventures rather than traditional dungeon crawls, combining them requires a structural and thematic approach.
1. Narrative & Level Integration
Both modules deal with urban murder mysteries, political intrigue, and shadowy organizations. Combining them into a single, contiguous mini-campaign yields the best results.
The Level Progression:
Act 1: The Veiled Society (Designed for Levels 1–3).
Start the characters in a major metropolitan hub (like Specularum or your campaign's capital). Act 2: The Assassin’s Knot (Designed for Levels 2–5).
Once the party deals with the localized faction warfare in the capital, they are dispatched to the insular, paranoia-fueled town of Garrotten to solve the assassination of the Baron of Restenford.
The Connective Tissue: Tie the Veiled Society (the Radu family's criminal enterprise) directly to the assassins in Garrotten. When the player characters smash the Veiled Society's ring in the capital, they discover correspondence or a contract leading directly to the hidden guild in Garrotten. This frames The Assassin's Knot not as a random side-quest, but as an investigation into the puppet masters who supplied the capital's underworld with their deadliest agents.
2. Converting the Mechanics to the Siege Engine
C&C uses the Siege Engine system—attribute checks based on whether a Prime Attribute is chosen (Challenge Base 12) or Non-Prime (Challenge Base 18).
Converting Thieving Skills & Clues
Both modules rely heavily on investigation, tracking, finding clues, and stealth. In original AD&D and Basic D&D, these were handled by rigid percentage rolls or flat X-in-6 chances.
The Clue Matrix: When players search for the three crucial clues in The Assassin's Knot (the string, the gray hair, the small button) or tail suspects through the streets during The Veiled Society’s riot, map these to Intelligence or Wisdom checks.
Searching a room for physical evidence: Intelligence Check (Add Rogue/Assassin class level if applicable).
Sensing if an NPC is lying or under duress in Garrotten: Wisdom Check (Insight/Empathy).
Interrogating a faction thug or corrupt guard: Charisma Check.
Setting Challenge Class (CC): Keep the CC low (0 to +2) to prevent investigative dead-ends. Remember, if a clue is mandatory to advance the plot, do not lock it behind a fail-state roll. Use the Siege Engine check to determine how long it takes or how much attention they draw while finding it.
Combat and Monster Compatibility
C&C monsters line up perfectly with early TSR modules.
Armor Class (AC): C&C uses ascending AC, while these modules use descending AC. To convert on the fly:
$$\text{C\&C AC} = 20 - \text{TSR AC}$$(Example: A Thug with AC 6 in B6 becomes AC 14 in C&C).
Hit Dice and Saves: Use the HD listed in the modules directly. When an NPC spellcaster casts a spell or an assassin uses a poison needle trap, the saving throw attribute maps seamlessly to C&C’s classification (e.g., Poison = Constitution save, Spells = Mental/Physical attributes depending on the spell type).
3. Running the Urban Elements in C&C
Because C&C streamlines the rules, you can focus on the fast-paced, high-tension narrative structures these modules require.
Handling the Riots and Chases (The Veiled Society)
The Veiled Society features a dynamic riot encounter and an urban chase sequence.
The Chase: Instead of checking abstract movement rates, use a series of Dexterity or Constitution Siege Engine checks (Challenge Base 12/18).
A character with Dexterity as a Prime attribute will easily navigate the crowded, narrow streets of Specularum, leaping over merchant carts, while a heavily armored Knight with Strength/Constitution Primes will have to rely on raw stamina to bulldoze through the crowd, creating a wonderful narrative contrast.
Tracking the Timeline (The Assassin's Knot)
The Assassin's Knot is inherently time-sensitive; if the players dawdle, the assassins commit more murders to cover their tracks.
Encumbrance and Travel: Use C&C’s simplified encumbrance system to track how quickly characters move through town.
Rogue vs. Assassin: If you have a Rogue and an Assassin in the party, give them distinct narrative spotlights. The Rogue's class features excel at gathering information in the taverns of Garrotten (Listen, Influence NPC), while the Assassin's features (Case Establishment, Sneak Attack) are perfect for tracking the local killers to their hideout and anticipating their next moves.
4. Campaign Adjustment Reference
| Module Aspect | Original System Feature | Castles & Crusades Adaptation |
| NPC Statblocks | Multi-page AD&D 1e breakdown | Use directly. Convert to Ascending AC ($20 - \text{AC}$). |
| Faction Alignment | Rigid Law/Chaos restrictions | Treat as societal factions; rely on C&C's fluid alignment definitions. |
| Investigative Magic | Speak with Dead / Know Alignment | Pelltar the Sorcerer explicitly notes magic won't easily solve the crime; enforce this to keep the mystery alive. |
| The Cutouts (B6) | 3D Cardstock buildings | Replace with theater of the mind or simple battle mats; emphasize the claustrophobic, dirty alleys of the city. |
Castle Keeper Note: In The Assassin's Knot, the Baron's body is mutilated to prevent low-level Raise Dead spells. Ensure your party's Cleric understands that the divine magic available at levels 2–4 cannot easily bypass this plot point, forcing them to rely on their wits and the Siege Engine rather than brute-force spellcasting.
To weld The Veiled Society (B6) and The Assassin’s Knot (L2) into a cohesive campaign, the Radu Family—the wealthy merchant-mafiosos who lead the Veiled Society—must serve as the connective tissue.
By positioning the insular town of Garrotten as either a financial asset, a clean-up crew, or a secret haven for the Radu enterprise, you turn the transition between modules into a natural escalation of the plot.
Hook 1: The Failed Clean-Up Contract (The Paper Trail)
The Premise: When the party finally breaches the Veiled Society’s inner sanctum or defeats their agents in the capital, they find that the Radu family was already preparing to cut their losses and silence everyone involved.
The Discovery: Among Anton Radu’s private ledgers or on the body of a high-ranking Society enforcer, the players discover a highly coded letter bearing a wax seal depicting a noose entwined with a dagger.
The Details: The letter is an invoice and a confirmation of a contract. The Radu family paid a massive sum of gold to an organization based in the remote town of Garrotten. The contract dictates the systematic elimination of several mid-level Veiled Society captains (and potentially the PCs themselves) to ensure no loose ends can tie the riots and murders back to the Radu patriarchs.
The Twist & Escalation: Before the party can act on this information, word reaches the capital that Baron Eric of Restenford (a close political or economic ally of the capital's ruler) has just been assassinated in his bed. The modus operandi matches the signature of the Garrotten killers mentioned in the Radu letter. The capital's authorities task the party with traveling to Garrotten to investigate the Baron's death, realizing that the Radu family’s conspiracy extends far beyond the city walls.
Hook 2: The Money Laundering Pipeline (The Poisoned Vine)
The Premise: Garrotten is a town built on a lie; its insular nature makes it the perfect place to hide dirty money. In this hook, the Radu family is the hidden financial backer of Garrotten's illicit economy.
The Discovery: While dismantling the Veiled Society’s smuggling operations, the party intercepts a heavily guarded caravan leaving the city. Instead of bringing contraband in, it is smuggling enormous wealth out—specifically, crates of minted coins, rare spices, and silks.
The Details: Shipping manifests and interrogation of the caravan master reveal that these assets are being routed directly to Harper’s Tavern or the Landston estate in Garrotten. The Radu family has been using Garrotten’s isolated location and corrupt leadership to launder the wealth they steal through protection rackets and extortion in the capital.
The Twist & Escalation: The party travels to Garrotten to freeze these assets and catch the Radu's financial contact. However, they arrive just as the town plunges into paranoia following the Baron’s murder. The local authorities (many of whom are on the Radu payroll) immediately view the PCs as prime suspects or dangerous agitators, forcing the party into a tense game of cat-and-mouse where finding the Baron's killer is the only way to clear their names and expose the money trail.
Hook 3: The Bloodline Alliance (The Rogue Faction)
The Premise: The political scheming of the Radu family requires absolute secrecy. When a prominent member of their operation threatens to break under pressure, they are exiled to Garrotten for "safekeeping."
The Discovery: During the climax of The Veiled Society, a key antagonist—such as Carina Radu or a high-ranking lieutenant who knows the absolute truth of the family's treason—vanishes from the city entirely, smuggled out via an underground river or hidden carriage.
The Details: Through street-level interrogation or tracking (using C&C Rogue/Assassin skills), the party learns that the fugitive has been sent to a remote, tightly controlled sanctuary where "outsiders are hated and questions are answered with a knife"—the town of Garrotten. The Radu family has placed this individual under the direct protection of the local assassin's guild.
The Twist & Escalation: When the party tracks the fugitive to Garrotten, they find the town completely locked down. Baron Eric was murdered just days before their arrival, and the local guard is looking for any excuse to hang strangers. The party must navigate the paranoid populace to find their original target, only to discover that their fugitive has used Radu gold to commission the Baron's death, completely destabilizing the region to protect their own skin.
Castle Keeper Integration Tip
The C&C Advantage: When introducing these hooks, utilize the Gather Information or Case Establishment class features of your party's Rogues and Assassins. Instead of just giving them the text of these hooks, let them roll an Intelligence or Charisma Siege Check (typically CC 2 or 3 due to the secretive nature of the Veiled Society) to uncover these connections piece by piece from the docks, taverns, and back-alleys of the capital.
