I let out a deep breath and turned back to Bess and George, feeling defeated.

“All right, Nancy,” said Bess. “Now you have to tell us. What’s going on?”

“Yeah,” said George. “And why couldn’t we have kept sleeping for a few more hours?”

I nodded. My friends were right: they deserved to know what was going on.

First I walked over to the dog plates hanging on Mrs. Park’s wall. “Emily said this store was important, right?” I began. “And that whoever was behind this did a project here. Well, I actually think they did three projects here.”

Bess and George stepped closer and looked at the plates. For a moment, they didn’t seem to understand what I was trying to tell them. But eventually Bess’s eyes lit up.

“Oh!” said Bess. “You think that whoever is behind this imprinted the modern-day images onto the DeSantos photographs in the same way Mrs. Park makes her plates.”

“Exactly,” I said. George stepped forward and ran her fingers over the images on the plates as I explained a bit more. “I looked it up, and it’s an easy enough process. You just cover the photograph with a certain type of glue, and the image transfers to the glue. When it dries, you carefully remove any paper on the back of the photo, and you have what’s essentially a decal, which you can stick on any surface.”

“But Nancy,” said George, “how would anyone manage to sneak one of the DeSantos photographs out of the museum? Wouldn’t Susan notice that a piece of her exhibit was missing? Or wouldn’t Mrs. Park realize there was a priceless piece of art in her store?”

The three of us looked in Mrs. Park’s direction. She had lifted up her glasses and was squinting at a piece of paper in her hands. She was clearly having trouble seeing it well enough to actually read it.

“Okay, maybe she wouldn’t have noticed,” conceded George. “But still, getting one of those photographs out of the museum would be really difficult.”

I shook my head. “I don’t think the photographs ever left the museum,” I said. “Whoever did all this could have just stuck the picture of me or Grace or Jacob on any piece of glass. As long as it was the same size as the photograph’s picture frame, they could just sneak into the museum at night and switch out the pieces of glass.”

“Isn’t there a lock on each of the picture frames, though?” asked Bess. “How would whoever was doing this know those combinations?”

“My guess is the combination on the picture frames is the same one Susan uses for the museum’s doors,” I said. “Whoever knew that combination could mess with any of the photographs they wanted.”

“So it has to be someone with that combination,” said George. “It has to be Susan, Beverly DeSantos, or Grace. But how do we know which one?”

“Actually,” I said, “I don’t think it was any of them. Grace knew the combination, so she could have just told whoever she was working with.”