Sixth Keystone?

I am also at the last chapter, and have only five keystones. I have a key; but no lock at the tree hollow. I unlocked it earlier and got the keystone. There are six chapters; but is there a keystone in the first? If there is, I cannot find it. Thanks for any help.

Here are the locations of the keys & locks.

Key locations:
- hanging on the wall in the workshop
- leaning against the tree trunk in the tree house
- on grandma's rocking chair in the cottage
- in the armoire in the butcher's house
- in the glass coffin at the lookout
- in the embers of the fireplace in the manor grand room

Keystone locations:
- hole in tree in manor back yard
- mouse hole in storeroom
- pile of wood beside scarecrow in Hallow Hills
- toolbox in shed at the woodland cottage
- junk pile in Scarecrow Alley
- crypt in lost graveyard

Thanks!!! I found the sixth keystone. I had never used the key on the toolbox in the shed. Now, I'm good to go!!!

You're very welcome. So glad I could help.