originally posted at https://canmom.tumblr.com/post/163190...

So our Battler has just, taking Beato’s bait, backed himself into a corner. He’s convincingly argued against any of the staff or guests being the murderer (except the mystery 19th guest), and more importantly, determined that it seems impossible for the door to have been locked on the outside without magic.

Our axioms:

1. ‘there are absolutely no types of hidden doors’
2. ‘this door is the only way in or out’
3. ‘the only way to lock this door is with Jessica’s single key or the master keys, only one of which is held by each servant’
4. ‘the window is locked from the inside’

That’s quite the puzzle. The most obvious solution seems to be that a master key could have been stolen from one of the servants. It can’t be Gohda, since he used his master key to open the door. It can’t be Kanon, since [his] key was on Jessica’s body. But we haven’t verified that Sayo, Genji and Kumasawa are still in possession of their keys.

The first move would be to verify that, but it seems too obvious, so let’s consider where we go next if it’s established the servants have maintained possession of their keys. This time they’ve searched the room and found no murderer, so we can’t argue the murderer was hiding in the room somewhere. The possibility of lockpicks is ruled out by axiom 3.

There’s the possibility the murder had a wax cast or similar and made a copy of Jessica’s key while in the room, though this would be very difficult to pull off quickly while leaving no residue, and any easily made cast would seem likely to break.

How will Battler solve this one?

Of course.

Battler begins by saying he won’t take the bait of quibbling over the lock. He tests the following statements:

• ‘Kanon was killed in this room’ - true
• ‘Kanon’s corpse is in this room’ - declined

He wonders which angle to go for: locking the door with no master key, killing two people inside a locked room, or escaping after killing both.

• ‘The last time it was locked was by a master key’ - declined

Noting a flaw in this method: Beatrice is not obliged to red-text a true statement. She can mislead Battler by declining to confirm something that’s actually true.

…and Battler makes the same observation as me right after I typed that lol. Beatrice responds by saying that time he had the advantage, but when she has the advantage, there’s no need to take the bait.

Beato tries to bait Battler into accusing Kumasawa or Genji. He tells her to shut up a moment so he can think.

• ‘When locked, it does not permit any form of entry or exit.’
• ‘No trick could have the effect of locking the door from the outside without using a key.’

I’m surprised we haven’t touched on the ‘stolen key’ hypothesis yet. We still haven’t verified the servants remained in possession of their keys. Given stealing a key was so crucial to Battler’s solution to the last puzzle, it seems like an obvious tack here.

Beatrice starts pressing Battler to suspect one of the known 18 people as he thinks about who could have stolen the key to the chapel as well. Come on, you have no reason to trust this 19th guest, whether or not she’s a witch. Blame her. Mundane Beatrice theories are where it’s at.

Battler makes this point, suggesting Beatrice snuck up in a cardboard box. That’s uh, kind of a bit too Metal Gear Solid, isn’t it?

Beatrice insists that this wouldn’t work for Jessica’s room, as a mundane Beatrice could not lock the door. Battler takes the challenge of arguing how a mundane Beatrice could do just that. Beatrice taunts him for refusing to suspect the other guests.

Come on, claim Beatrice stole the key from one of the servants. That’s my main hypothesis, I want to see that tested!

Battler accuses her of trying to ‘fork the rook’ which is a chess idiom I’m not really familiar with.

Narrative!Battler says ‘resign’. In this case, saying he can’t figure out who killed Jessica, if not Kanon. The chapter ends and the clock advances to 1pm.

Ugh, I want to see my hypothesis tested. Is it impossible that Beatrice stole Kumasawa’s key, Genji’s key or Sayo’s key at some point, and they haven’t noticed?

Anyway, the next chapter is called Wolves and Sheep Puzzle, so we’ll finally find out what puzzle they’re referring to.