Prologue Walkthrough

The prologue of The Mermaid Mask establishes the central mystery that drives the entire twelve-hour investigation: Captain Magnus Mortuga has been murdered aboard his legendary submarine, and the crime scene is a locked room inside the Illusion Theatre with no obvious way in or out. You play as Detective Grimoire, accompanied by his sharp-tongued partner Sally Spears, as the pair are summoned to the coastal town of Silkwirm-on-Sea. SFB Games delivers a classic point-and-click opening that immediately teaches exploration, dialogue, inventory management, and the importance of examining every object twice. Before you ever descend into the Mortuga Submarine, the prologue at Stonetop Inn grounds the story in place, personality, and the first mechanical puzzles that recur throughout the case.

Arriving at Stonetop Inn

Your investigation begins at Stonetop Inn, the weathered establishment where Mortuga's crew and associates have gathered in the wake of the captain's death. The inn serves as a narrative hub before the submarine opens fully, and nearly every screen contains inspectable hotspots marked by Grimoire's familiar magnifying-glass cursor. Talk to the patrons in the common room and note which characters mention the submarine, the theatre, or the captain's final hours. Captain Seafoam provides the official account of discovering the body, while innkeeper gossip hints at tensions that will matter later during crew interviews. Collect every dialogue topic available before moving on; the game rarely gates story progression behind obscure hidden clicks, but thorough conversation unlocks additional suspicion notes and map annotations that save time in Act Two.

Explore each inn location methodically: the lobby, guest corridors, the proprietor's office, and the exterior cliff path. Clues here tend to be observational rather than puzzle-based—photographs, receipts, nautical charts, and personal effects that foreshadow submarine rooms you have not yet visited. Use 3D clue inspection whenever an object rotates in your inventory; some prologue evidence contains markings visible only from the reverse side. If you are playing on Nintendo Switch 2 with mouse mode enabled, precision inspection feels nearly identical to the PC experience. Track discoveries on the Evidence Checklist if you want a structured record of the roughly fifty clues scattered across the full game.

Mess Hall Dial Puzzle

The first major mechanical challenge appears when Grimoire and Spears gain access to documentation referencing the submarine's Mess Hall combination system. Although the physical dial panel is aboard the Mortuga, the prologue introduces its logic through a schematic pinned near the inn's kitchen service corridor—a teaching moment before you encounter the live puzzle downstairs on the sub. The Mess Hall dials use three rotating faceplates marked with triangle, square, and pentagon motifs. The solution depends on counting corners on adjacent symbols rather than memorizing a numeric code, a design choice typical of SFB Games' preference for deductive reasoning over brute force.

In the prologue, examine the schematic carefully and rotate your copy in inventory until Spears comments on the corner totals. The triangle contributes three, the square four, and the pentagon five; the dial positions must align so that shared edges satisfy the totals etched beneath each plate. Write down the final orientation shown in your case notebook because you will replicate it aboard the submarine. If you get stuck, remember that the keyhole icon in the upper-right corner of puzzle screens both confirms valid completion and offers contextual hints after a short delay. See the dedicated Mess Hall dials solution page for the exact final positions once you reach the live panel.

Illusion Theatre Locked Room

The prologue's dramatic centerpiece is the discovery that Mortuga died inside the Illusion Theatre—a performance chamber aboard the submarine sealed by an elaborate stage lock. During the inn sequence, Grimoire reconstructs the locked-room problem using witness statements, a theatre seating chart, and a partial backstage diagram contributed by Symmetry Silkmoth. The game walks you through the constraints: the outer hatch was bolted, the stage lift was inactive, and no hidden passage appears on official Mortuga blueprints. Your job in this segment is not yet to solve the locked-room trick—that revelation comes mid-investigation—but to catalog every claim made about who had access and when.

Pay attention to the Illusion Theatre props list pinned in the inn's reading nook. Items like the collapsible scrim, the mirror cabinet, and the submarine-themed trapdoor platform each receive a notebook entry that becomes searchable later. The prologue ends with Grimoire declaring the theatre a priority crime scene and securing permission from Seafoam to board the Mortuga at dawn. This transition unlocks submarine exploration on the world map. Players who rush the inn may miss optional ambient dialogue from Mariana Moon about the theatre's final rehearsal, dialogue that subtly informs the cauldron deduction ahead.

Ancient Cauldron Deduction

Before leaving Stonetop Inn, Grimoire assembles the prologue's closing deduction scene around an ancient cauldron replica displayed in the inn's maritime museum alcove. The cauldron—matching the one found near Mortuga's body—bears alchemical sigils that correspond to crew roles aboard the submarine. This is a structured deduction challenge rather than a combination lock: you drag symbolic tokens representing motives, access, and opportunity onto the cauldron rim until Spears validates the logic chain. Incorrect placements produce gentle feedback from Grimoire without resetting progress, aligning with the game's accessible hint philosophy outlined in the hint system guide.

The correct deduction path establishes that Mortuga's death required intimate knowledge of both theatre mechanics and submarine duty rotations—a fact that narrows the suspect pool before formal interviews begin. When the cauldron sequence completes, the game awards a prologue achievement progress tick toward Steam achievements and unlocks fast travel to the Mortuga dock on the world map. Take a moment to review your evidence notebook; the prologue intentionally leaves some threads unresolved, teasing puzzles like the switchboard plugs and card lens arrangement waiting deeper inside the vessel.

• Talk to every NPC at Stonetop Inn before requesting submarine access.
• Photograph or note Mess Hall dial schematic orientations when Spears comments.
• Inspect all Illusion Theatre props on the inn reference board.
• Complete the cauldron deduction to unlock Mortuga dock travel.
• Use the keyhole icon if any prologue puzzle screen feels unclear.