The Mermaid Mask Walkthrough Guide: All 8 Suspects (2026)

The Mermaid Mask walkthrough guide starts right where most players get stuck: eight strange suspects met, a captain dead beside a stone cauldron, and the case-building screen still won't budge. It maps the Mortuga Submarine, names everyone aboard, and explains how the investigation actually unlocks, without handing you the final answer SFB Games spent seven years building toward.

TL;DR: The Mermaid Mask splits into two investigation phases divided by a single checkpoint: reporting to Captain Sinthia Seafoam. Before that report, gather all 48 pieces of evidence, talk to all 8 named suspects, and expect to solve at least 13 hands-on puzzles. Reporting opens new areas, including the Aft Deck and Diving Tank, so finish the first phase before you move on. No single authoritative walkthrough of the final deduction exists yet, so this guide covers structure and strategy rather than the ending itself.

The Mermaid Mask walkthrough: where to start (quick answer)

Explore freely before reporting anything. The submarine's rooms unlock in roughly this order: Foredeck, Parlor, Mess Hall, Illusion Theater (the crime scene), then Dream Chamber, both Bunk Rooms, Child's Room, Cargo Hold, Engine Room, and Airlock. Talk to all 8 suspects before chasing puzzles, since several clues only appear after a specific conversation happens first.

The Mermaid Mask walkthrough guide: key takeaways

• 8 named suspects live or work aboard the Mortuga Submarine, and each needs a separate "suspicion" unlocked
• 48 pieces of evidence exist before you report to Captain Seafoam, which then opens a second investigation phase
• At least 13 distinct puzzle types appear in that same pre-report window, from dial locks to a pinboard character puzzle
• Some evidence only unlocks by asking the right suspect about a specific other suspect, not by searching rooms
• The Captain's Quarters and Captain's Cabin stay locked until you solve the Child's Room doll puzzle for a key item
• The Bilge requires a light source, which Dirk's cell phone provides once you have it
• No verified account of the final "who killed Mortuga" deduction exists in an authoritative source as of this guide's research

Overview

This guide reflects The Mermaid Mask at version 1.0, the July 16, 2026 launch build, cross-checked against Steam Community guides written by players who finished the case. It covers the investigation structure: which rooms open when, who the suspects are, what the puzzles ask of you, and how the suspicion system decides you've done enough to accuse someone. It doesn't cover the final deduction screen or reveal who killed Captain Magnus Mortuga. That reveal is the entire point of a locked-room mystery, and SFB Games built the whole game around the reader working it out themselves. Spoiling it for someone who hasn't played does more harm than a missed puzzle answer.

If you already finished the case and want to sanity-check a specific puzzle, Steam Community's guide section for this game (linked in References) has screenshot-by-screenshot answers for individual puzzles. This article is for players who are mid-investigation and stuck on structure, not a specific dial combination.

You'll want a completed playthrough of the tutorial first. Sally and Grimoire's opening sequence at the Stonetop Inn, then boarding the submarine, teaches the examine-and-rotate interface this guide assumes you already know.

Step-by-Step

Before you start: understand the report checkpoint

The Mermaid Mask splits into two halves around a single checkpoint. Before you report your findings to Captain Sinthia Seafoam, you can explore the submarine freely, revisit any suspect, and re-examine any clue. Reporting moves the case into a second phase and opens new areas, including the Aft Deck and Diving Tank. What isn't confirmed anywhere is whether unfinished pre-report business (an evidence item you missed, a suspicion you never unlocked) stays reachable afterward. Treat it as a one-way door. Gather all 48 pieces of evidence and unlock all 8 suspicions before you report, rather than assume you can circle back.

Meeting all 8 suspects aboard the Mortuga Submarine

Six suspects are reachable the moment you're free to explore: Doctor Zacharias Zephyr in the Dream Theater, Dirk Dansom and J.D. Wirman sharing a Bunk Room, Mariana Moon in the Cargo Hold, Godrik Gripp in the Engine Room, and Madam Tadpole in the Airlock. The remaining two, Captain Sinthia Seafoam and stage performer Symmetry Silkmoth, require a short back-and-forth: knock on the Parlor door, get redirected to Symmetry's Child's Room, find nobody there, go back to Seafoam, and she'll finally send you through properly.

Each suspect has a distinct hook worth noting for later. Zephyr collects rare artifacts, and his Dream Chamber is full of them. Wirman is a novelist whose first book, "The Hex of the Helmsman," comes up early in conversation. Gripp will try to sell you three separate items the first time you speak to him, in a bit that's pure comic relief but also introduces his cane as an evidence item. Moon tracks where everyone was standing at any given moment, which becomes directly useful once a puzzle asks you to place every suspect in a specific room. None of this spoils who's guilty. It's the same information the game hands you in the first hour regardless.

Wirman's bunk room, shared with fellow suspect Dirk Dansom, holds two of the investigation's early puzzle clues: an action figure and a symbol-locked cell phone.

Room by room: what to search first

After the Illusion Theater crime scene, head to the Mess Hall for the Shape Dials puzzle and the Control Room for the Switchboard puzzle, since both gate a piece of evidence you'll want early: the Sun Tablets and the Captain's Log respectively. The Dream Chamber's Dropper Vials puzzle needs a conversation with Zephyr first, so don't waste time on it before you've spoken to him.

Two rooms stay locked until you clear a specific earlier step. The Captain's Quarters opens once you solve the Doll Lenses puzzle in the Child's Room and identify the resulting Glass Eyeball as a key. The Bilge needs a light source, which you won't have until Dirk's cell phone is in your inventory. Save both for later in your first pass rather than backtracking repeatedly.

A handful of evidence items don't sit in any room at all. They unlock only through conversation chains: asking Sinthia about Symmetry lets you ask Symmetry about her locket, asking Symmetry about Gripp lets you ask Gripp about his cane, and asking Gripp about Mariana lets you ask her about her pipe. If your case file feels thin compared to this guide's evidence count, this conversational layer is often why.

The investigation puzzles you'll hit early

The Mermaid Mask front-loads its puzzle variety. Before your first report, expect to solve some version of these: Shape Dials (Mess Hall), Dropper Vials (Dream Chamber), Cell Phone Symbols and Typewriter Dials (the shared Bunk Room), Doll Lenses (Child's Room), a Character Pinboard (Cargo Hold), a Compass puzzle (Engine Room), Diving Helmet Dials (Airlock), the Switchboard (Control Room), a Piggy Safe (Sinthia and Symmetry's Bunk), rotating Orbs (Bilge), and a Model Town boat puzzle (Captain's Cabin). A thirteenth, a Card Suits puzzle hidden in the Illusion Theater, only appears after specific prior conversations and isn't required to progress.

The pattern across nearly all of them: read every hint line the game gives you before touching a dial. The Compass puzzle, for instance, tells you outright that none of the compasses point north, and each of the four decoys behaves differently when you rotate the disc around it. The Switchboard puzzle explicitly allows redundant, overlapping connections with no penalty, which is the opposite of how most players instinctively approach a wiring puzzle. If a puzzle feels unsolvable, re-read its instruction text before assuming you've misread the visual clue.

GODEEPER: If The Mermaid Mask's puzzle fairness has you curious how it holds up against the rest of the review, the spoiler-free verdict covers the 3D clue system and the Budapest Art Orchestra score. The Mermaid Mask Review 2026 →

How the suspicion system actually triggers

Each suspect has an individual "Suspicion" that unlocks once you've gathered the relevant evidence, read or listened to all of it, and asked the right people the right questions. The game notifies you the moment the final piece clicks into place, but it doesn't tell you which piece was missing in advance. Two behaviors matter most: read every piece of text evidence in full (letters, journals, newspaper clippings), and go through Dirk's cell phone completely, meaning the call log, contacts, and every message.

If a suspicion won't unlock and you've checked every room, the missing piece is often a conversation you haven't tried yet, not an object still hiding somewhere. Ask each suspect about each of the other suspects by name. Several of the game's most important evidence items, including a locket, a cane, and a pipe, exist behind exactly that kind of exchange and never appear as a pickable object in any room.

Tips

Listen to full recordings before moving on. Evidence like the Wooden Pipe and the Film Projector plays as audio or video, and the game expects you to sit through the entire thing, not just the first line. Suspicions have stalled for players who treated a recording as flavor text instead of a clue.

Don't skip the phone. Dirk's cell phone holds call logs, emails, and text messages that read like a completely separate side-story from the rest of the investigation, and at least one suspicion depends on going through all three tabs, not just the obvious one.

Track who's missing from your suspect count. If you have fewer than 8 unlocked suspicions and you're ready to report, you haven't actually finished the pre-report phase. Going back through each suspect's individual profile screen shows exactly which clue slots are still empty for them.

Second playthroughs can unlock things in a different order. One player who documented two separate runs found that the specific clue or conversation that finally triggers a given suspicion wasn't fixed between them; it depended on what order they'd investigated things in. Don't assume a guide's exact trigger sequence will match yours click for click.

Use the case-building screen as your checklist, not just your answer submission tool. Revisiting it mid-investigation shows which evidence categories you have gaps in, which is faster than mentally tracking 48 individual items.

Common Mistakes

Reporting to Captain Seafoam before you're actually done. The pre-report phase is where all 48 evidence pieces and all 8 suspicions live. Reporting moves you into a new phase with its own areas to explore, and there's no confirmed way back to finish loose ends from the first half. Treat "ready to report" as "fully investigated," not "investigated enough."

Skipping the Illusion Theater's hidden Card Suits puzzle. It's easy to miss because it only appears after a specific chain of conversations (asking about the Illusion Poster, then asking multiple suspects about Symmetry). It's not required, but the Film Projector reel it unlocks fills a gap other evidence leaves open.

An early case-building challenge from the tutorial. The full version of this screen, used for every suspicion, works the same way: drag evidence and phrasing into the blanks to build a statement.

Treating the compass and switchboard puzzles as pure trial and error. Both explicitly reward reading the in-game hint text first. The compass puzzle names each decoy's specific behavior in its intro line, and skipping past it turns a two-minute puzzle into a fifteen-minute one.

GODEEPER: Investigation mechanics aren't unique to submarines. Security 51 runs a similar "gather evidence, build a case" loop through a very different lens. Security 51 Review 2026 →

Assuming the Bunk Room puzzles are optional. The Typewriter Dials puzzle in particular gates the Handwritten Letter, which multiple suspects' evidence lists include. Skipping it because it looks decorative stalls at least two suspicions later.

The Mermaid Mask currently sits at Overwhelmingly Positive on Steam, with 99% of 1,971 user reviews positive at the time of this guide. That reception tracks with what the investigation structure actually rewards: patience with text, not puzzle-solving speed. If you want a lighter recommendation for a similar price point, Best Indie Games Under $20 rounds up other budget picks from the same release window.

Frequently Asked Questions

Is there a full walkthrough for The Mermaid Mask? Not an authoritative one yet. The Mermaid Mask launched July 16, 2026, and no single trusted source has published the exact final deduction. Steam Community guides cover the investigation phase and individual puzzles in detail, which is what this guide draws from.

How many suspects are in The Mermaid Mask? Eight. Madam Tadpole, Dirk Dansom, Doctor Zacharias Zephyr, J.D. Wirman, Godrik Gripp, Captain Sinthia Seafoam, Mariana Moon, and Symmetry Silkmoth all live or work aboard the Mortuga Submarine. Every one needs an unlocked suspicion before the case can close.

How many puzzles does The Mermaid Mask have? At least 13 distinct hands-on puzzles appear before you file your first report to Captain Seafoam, covering dial locks, symbol matching, and object rotation. More puzzles follow in the second investigation phase, after that report.

What happens when you report to Captain Seafoam in The Mermaid Mask? Reporting moves the case into a second investigation phase and opens new areas, including the Aft Deck and Diving Tank. Whether unfinished first-phase evidence stays reachable afterward isn't confirmed, so gather all 48 pieces and unlock every suspicion before you report.

Do I need to play Tangle Tower before The Mermaid Mask? No. Each Detective Grimoire case is self-contained. Returning players will recognize Grimoire and Sally, but the Mortuga Submarine's mystery, cast, and clues stand entirely on their own.

Where can I find puzzle-by-puzzle answers for The Mermaid Mask? Steam Community hosts several player-written guides with screenshot solutions for individual puzzles, including dedicated pages for the compass, typewriter dials, and cargo pinboard. Check the game's Steam Community Guides tab if you're stuck on one specific screen.

Is The Mermaid Mask worth playing if I already read a walkthrough? Yes, though it changes the experience. The puzzle logic and voice performances hold up on a guided run, but the deduction moments land harder blind. Consider using a walkthrough only for a single stuck puzzle, not the whole case.

Related Reading

• The Mermaid Mask Review 2026: the spoiler-free verdict on the 3D clue system, the cast, and whether the case-building loop holds up.
• Security 51 Review 2026: another 2026 indie built around gathering evidence and building a case, in a checkpoint-horror setting instead of a submarine.
• Black Jacket Review 2026: a different kind of tension-driven indie for readers who want more from the same release window.
• Best Indie Games Under $20 2026: seven more budget picks if The Mermaid Mask's price point is your ceiling.

References

• The Mermaid Mask on Steam: official store page, current pricing, and Steam Community guides section.
• "The Mermaid Mask - Guide" by bearsbearsbears on Steam Community: player-written walkthrough covering the pre-report investigation, room order, evidence list, and puzzle solutions used as a structural source for this article.
• SFB Games official site: developer of The Mermaid Mask, Tangle Tower, and Crow Country.
• The Mermaid Mask launch trailer (YouTube): official trailer from SFB Games.