Deduction Answers and Final Case Conclusion

By the late deductions in The Mermaid Mask, the Case File—your notebook of clues, testimony, and unfinished conclusions—looks as if a seaside curiosity shop capsized into it. If a prompt feels vague, stop cycling through every tile. Check the named object and hotspot below, then enter the selections in order. That keeps the case feeling like detective work instead of evidence bingo.

The answer lists use the wording shown in the game. Choose these entries as written; similar words or theories are not tested substitutes.

Prologue: The Beginning — What Happened to Mortuga?

Hint: The locked door makes the scene look impossible, but the open Stone Cauldron shows what Mortuga appeared to be doing before his death.

Required clues and details: Inspect the Chalk Outline, locked Bulkhead Door, Mortuga’s Blood, and open Stone Cauldron. Rotate the cauldron to see its interior.

Answer — select in this order:

Magnus Mortuga
unlocked
The Cauldron
and was killed by
what was inside

The completed conclusion is: Magnus Mortuga unlocked The Cauldron and was killed by what was inside. When Grimoire asks what stands out inside it, select the scratches. This begins Chapter One.

Tip: If the deduction will not start, return to the Illusion Theatre and inspect the Chalk Outline after the other crime-scene objects. If the sentence is complete but the chapter has not changed, rotate the cauldron and select the scratches. That tiny hotspot is carrying an indecent amount of drama.

Chapter One: The Curse in the Cauldron — Case-Wide Checkpoint

Chapter One leads through eight personal Suspicion confrontations instead of another stand-alone murder sentence. Complete all eight, report to Sinthia, and finish the later submarine sweep. The next case-wide reconstruction follows after you open the Black Box, recover The Mermaid’s Tongue, connect the Iron Bell to the cauldron, and inspect the foreign metal fragment in the bell.

FINAL-CASE SPOILER WARNING: CULPRIT, METHOD, MOTIVE, TIMELINE, AND ENDING

Stop here if you only wanted the opening deduction. Everything below reveals the locked-room method, murderer, motive, and ending.

Chapter Two: The Box That Would Not Open — How Does the Bell Fit the Cauldron?

Required clues and details: In the Captain’s Cabin, inspect the fitting hanging inside the Iron Bell. In the Illusion Theatre, inspect the matching shape on the Stone Cauldron lid.

Connection order:

The Hanging Part
slots into
The Shape On The Lid
to lock or unlock the cauldron

Move the table in the Captain’s Cabin, lift the rug, and open the hatch above the Illusion Theatre. Downstairs, close the cauldron and rotate the loose pipe behind the Illusion Poster to lower the bell. Try both bell handles, then turn them together with Sally. Inspect the foreign metal piece when the mechanism opens.

Chapter Two — The Unveiling of the Illusion Theatre: How Was Mortuga Killed?

Required clues and inspected details: Prepare the Iron Bell, the vision inside the Hex Bottle, the bell’s metal fragment, the necklace-shaped mark on the Mourning Envelope, the necklaces in the HER Painting and on the Figurehead, and recording four from the second tape inside the Wooden Pipe.

A Murderer — select in this order:

Choose A Murderer.
Select The Iron Bell.
Select the Hex Bottle and inspect the vision of Mortuga lowering the bell.
Choose He did it by himself.
Inspect the foreign fragment on the bell.
Connect A Metal Thing → was wedged into → The Iron Bell → to kill Mortuga when it rotated around.
Choose It was longer, but it’s cut in half.
Select the Mourning Envelope and inspect the necklace imprint.
Select the HER Painting and inspect Felicia’s necklace.
Select the Figurehead and inspect its matching necklace.
Select the Wooden Pipe, open its second tape, and play recording four.

The Necklace Key needle was fitted into the Iron Bell. Mortuga operated the bell himself, and the hidden needle cut his throat as the mechanism rotated around the cauldron. Part of the weapon remained in the bell, while Gripp later concealed the usable needle inside his compass.

Chapter Two — The Unveiling of the Illusion Theatre: How Was the Locked Room Entered?

Required clues and inspected details: Check the hatch between the Captain’s Cabin and Illusion Theatre, the Eyeball Key, The Vent Under The Cauldron, the center of the Ship Wheel, the broken Moon Vial and separated dropper, page one of the Captain’s Log, and the direction of Mortuga’s Blood.

…And A Thief — select in this order:

Choose …And A Thief.
Choose The culprit didn’t need to use the bulkhead door.
Identify the hatch from the Captain’s Cabin.
Select the Eyeball Key.
Connect The Eyeball Key → fell through → The Vent Under The Cauldron → and landed in the Bilge.
Choose The culprit tilted the submarine.
Inspect the center mechanism of the Ship Wheel.
Choose A clue found at the crime scene.
Select the Moon Vial, then inspect its dropper near the Ship in a Bottle.
Select page one of the Captain’s Log.
Inspect Mortuga’s Blood.

Gripp tilted the submarine so the Eyeball Key fell through the vent and into the Bilge. He recovered it, unlocked the Captain’s Cabin, and used the ceiling hatch while the Bulkhead Door remained locked. After Mortuga triggered the rigged bell, Gripp entered the theatre, took The Mermaid’s Tongue and the remaining weapon, and climbed out through the hatch. Very theatrical. Entirely fatal.

Chapter Two — The Murder of Magnus Mortuga: What Was in the Cauldron?

Required clues and inspected details: Prepare The Mermaid’s Tongue, page five of the Caretaker’s Journal, the Underwater Photo, Ocean Map, Ripped Scroll, Ocean Treasure, Mortuga’s film and audio, the Handheld Radios, Ship in a Bottle, Model Town, and Broken Compass.

The Mermaid’s Tongue report — select in this order:

Report The Mermaid’s Tongue.
Select the Caretaker’s Journal and open page five.
Select the Underwater Photo.
Choose That’s because it isn’t complete.
Connect Ocean Map first and Ripped Scroll second.
Select Ocean Treasure; inspect the sharp coral and gemstone eyes.
Choose Because he wanted to keep it hidden from everyone.
Inspect the cauldron beneath the bell on the Ripped Scroll.
Choose Because they were the third person on the Dearest Selena voyage.

The Third Person report — select in this order:

Select Mortuga’s film reel and inspect the person peeking through the doorway near the middle of the film.
Select Mortuga’s audio recording and choose Mortuga is talking to the third person from the voyage.
Select the Handheld Radios.
Connect The Ship in a Bottle → rattles when you shake it, because → A Model of Someone Else → is hidden inside the ship.
Choose The ship in a bottle rattling when you shake it.
Compare the Ship in a Bottle with the Model Town. Choose Godrik Gripp as the missing person, then inspect the detailed model of Gripp’s shop.
Inspect the Service Record sticker on the back of the Ocean Map.
Break the Ship in a Bottle to reveal Gripp’s hidden model.
Choose Gripp still has both the murder weapon and the key.
Select the Broken Compass, open it, and choose the necklace key needle.

The compass evidence completes the accusation automatically. Gripp was the concealed third traveler aboard the Dearest Selena, helped fund the submarine’s search, and was with Mortuga when the Black Box revealed Felicia’s Necklace Key. The hidden bottle figure proves his old voyage; the needle inside his compass ties him to the bell trap.

Chapter Three: The Wayward Navigator — Rebuilding the Old Voyage

As Gripp explains the Dearest Selena voyage, use these story clues when their prompts appear: Ocean Map, Iron Bell, The Mermaid’s Tongue, Ship Wheel, and Cornelius Cane. During the submarine’s creation story, select the Inn Deeds when the fate of the old ship and Gripp’s payment are questioned.

The chain shows that Gripp joined Mortuga and Felicia on the voyage, heard the Mermaid, and became determined to find her again. A broken piece of the old ship’s wheel became Cornelius Cane. Gripp later paid for the submarine project using the Inn Deeds so the search could continue.

Chapter Three — Who Did What Aboard the Submarine?

The first board asks you to assign two information cards to each person. You may move the cards in any order, but all sixteen must occupy these final slots before you confirm:

Godrik Gripp: Commissioned the submarine as a way to search for The Mermaid’s Tongue; Was with Mortuga when he opened the Black Box and discovered the Necklace Key.
Dr. Zephyr: Was asked to smuggle The Mermaid’s Tongue onto the submarine; Stole The Mermaid’s Tongue from the Airlock and put it in his Cabinet of Curiosity.
Symmetry: Was invited to work alongside Dr. Zephyr in the Dream Chamber; Performed a magic act for Mortuga which appeared to make him miserable.
Madam Tadpole: Was saved from drowning by Mortuga; Offered to take over from Mortuga as a way of freeing him from his burden.
Sinthia: Sought out the submarine to reclaim ownership of it; Mortuga wrote a contract which she found after his death and forged his signature.
J.D. Wirman: Was sent a letter explaining how to access the Mortuga submarine; Considered using Mortuga’s death as the story outline for his next book.
Dirk: Was sent to spy on Wirman and report back to his employer; Tried to convince Wirman to kill Markus Mordoom.
Mariana: Was hired by Mortuga to find information about Felicia Stonetop; Brought the Black Box onto the submarine and gave it to Mortuga.

Four panels then need corrections. You may clear the panels in any order; within each panel, choose the entries from top to bottom as listed:

Madam Tadpole: Godrik Gripp, then Felicia Stonetop.
Sinthia: the Command Contract, the Message in a Bottle, then the Inn Deeds.
J.D. Wirman: the Handwritten Letter, Magnus Mortuga, then Felicia Stonetop.
Symmetry: The Star-Gazing Girl, the Mourning Envelope, then Felicia Stonetop.

The corrections show that Mortuga still needed Gripp to reveal Felicia’s location, Sinthia was not the intended recipient of the completed contract, Mortuga wrote the false letter that lured Wirman aboard, and Felicia’s death—not Symmetry’s performance—caused Mortuga’s misery.

Chapter Three — Why Did Mortuga Open the Cauldron?

Choose I think he wanted to hide The Mermaid’s Tongue somewhere else. Mortuga knew the Necklace Key was aboard and feared what Gripp would do with it. Gripp saw the key as his chance to use the Tongue, so he rigged the Iron Bell, killed Mortuga, and took the mask.

The final timeline has one extra twist worth pinning to the corkboard. After leaving through the hatch, Gripp tried to use the mask on the Aft Deck. Tadpole stopped him, and the mask ended up in the Airlock, where Zephyr found it and hid it in his Cabinet of Curiosity. This is why the mask is found with Zephyr even though Gripp built the murder trap.

Chapter Three — Ending Route

After the confession, Gripp takes The Mermaid’s Tongue again and runs. Follow him to the Captain’s Quarters, inspect the dropped Fixed Compass, and check the Fore Deck door. After the Mermaid drags the submarine underwater and releases it, present the Fixed Compass to Sinthia. Speak to everyone in Town Square to finish the ending and start the credits.

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