The door into the little room from the hallway was odd, which he didn't realize while he was staying in that room during the time he was working on the one that ended up his own bedroom. ...or while he was pulling up the carpet and taking down the paneling in this one.
When he got to the paneling behind the door ... that was when he saw the one thing that made him start to seriously think about all the things he'd found in the little room.
The little room didn't have a knob on the inside of the door.
...and there was no latch at the one knob it had.
The latch was a spring-loaded ball at the very top of the door that sank into a hole in the upper frame. It was tight. While the door could be opened easily from the outside ... you still had to give it a push, but just a small one ... it couldn't be opened from the inside. ...at all.
The only purpose Michael could imagine for the knob on the hall-side of the door was simply ... for closing it.
From the inside, it would have taken nothing less than a large screwdriver to pry the door with enough force to overcome the spring latch. And it wasn't openable at the latch if you didn't have something to stand on high enough that you could reach it, something to force the ball down, keep it down, and then something to keep the door from closing again, until you could get whatever you were standing on out of the way.
He finally realized that the little room door wasn't ever going to be opened from the inside if you were a child.
With all that he'd finally intended to do that day, all he actually ended up accomplishing was just fixing the one door, so it would open from the inside, and taking them both out.
All in all, that wasn't all that much. But it let me not have to start sanding the floor, yet.
And he was right. It wasn't much.
But it was enough. ...apparently.
That ... was the night it started.

Alia is a stand-alone book in the Horseless Horsemen series. The series is Paranormal Suspense and Dark Fantasy Horror, and it can get a little gruesome, sometimes. ...particularly in the earlier trilogy.
Alia is the ghost of a nine year old girl. After being kept a prisoner in her room, she woke up knowing that she had been buried under a tree in the back yard. For well more than a half-century, she couldn't leave her room, even though the door might be wide open. ...until that door was finally fixed.
Michael bought the house. ...and ended up with far more than he'd thought he had, when the ghost living there made herself known. After getting to know her a little better, she started telling him about children who had been murdered and needed to be freed from where they were buried, because they didn't know they were dead.
Together, they work to free the souls and answer the question: Why were they murdered?