As he's sorting, he finds a packet of letters to Alice Drablow from someone named Jennet. Hm. It seems she's a relative of Mrs.Drablow who had a child out of wedlock and gave him up to the Drablows to raise.
Arthur starts to get a real bad feeling about this whole thing.
Apparently Spider does too, because he starts to growl again. They run outside, where Arthur again hears the horrifying sound of a pony and trap getting stuck and a child drowning.
But this time, he realizes that the sound isn't real. It's a ghost sound.
We're not sure if this is better or worse ...
They scamper back inside. Spider growls and runs off, leading Arthur up the stairs and to the locked room.
The formerly locked room.
Now, the door is wide open.
He realizes that the sound he was hearing was the rocking chair. Because the chair is rocking by itself, but there's no one else in the room.
Arthur looks at the toys and contents of the room for a while, trying to figure out a rational explanation—but there isn't one.
Giving up, he returns to his room and goes to sleep.
Yeah, that was the part we couldn't believe either.