My daughter is six years old. She still sleeps with a stuffed elephant named Peanut. She puts ketchup on her scrambled eggs and thinks that is completely normal. She is the most ordinary, happy little kid, and I say that because what I’m about to tell you does not feel like it belongs in a life like hers.

It started with a drawing.

Her class had an assignment. Draw your family. Draw who lives in your house. Simple enough. Mia drew me. She drew her brother, Caleb, who is nine. She drew our dog, Biscuit. And she drew a man standing near the back door. Tall, stick-figure arms, a red hat on his head.

I don’t know anyone with a red hat.

Her teacher, Ms. Fontaine, called me that Thursday afternoon. She was calm about it, which made it worse somehow. She said, “Mia told me the man in the drawing comes at night. She said he uses the back door.”

I actually laughed. Not because it was funny. Just because my brain needed a second.

I told Ms. Fontaine it was probably her imagination. Kids that age mix up dreams and real life all the time, right? I thanked her and hung up. Then I sat in my car in the school pickup line and stared at nothing for about three minutes.

The thing is, my ex-husband Marcus is not allowed at this house. Court order. He has supervised visitation every other Saturday, $180 a month for the monitor, and he does not come here. That was the whole point of the agreement. That was the thing I fought for.

So I told myself it was nothing.

I checked the Ring camera that night. Front door, driveway, all clear. No one. I almost left it at that.

But I kept thinking about the red hat.

I walked around the outside of the house the next morning, just to look.

And I noticed the side yard, the narrow strip between the fence and the garage, had no camera on it at all. There is a gate there that leads to the backyard. I never really thought about it because the gate has a latch that’s always locked.

Or I thought it was always locked.

I went to Costco that afternoon. Bought a small security camera, $89. Set it up pointed at the side gate before the kids got home from school. I didn’t tell anyone. I’m not sure why. I guess I didn’t want to feel crazy if it turned out to be nothing.

The first night, I barely slept. I kept waking up and looking at my phone.

At 11:47 PM, I got a motion alert.

I opened the app and my stomach just dropped out of me. Not like a movie. More like I went completely still and everything got very quiet. There was a man walking through the side gate. Tall. Dark jacket. Red baseball cap pulled low.