The door was the space between the Triceratops horns.

I put the pages together. Same opening. Same proportions. Now it sat below a waterline in the reflection of a Plesiosaurus.

The animal itself was ordinary enough for the Archive: long neck, small head, four flippers. Another real prehistoric reptile that was not a dinosaur.

Its reflection belonged entirely to the notebook.

I drew a shoreline around it. Then a second version, with the creature seen from below. The first looked like a monster arriving. The second looked like an animal going somewhere.

The change was mine. Position. Framing. An assumption I hadn't noticed making.

Perhaps that was the pattern. Not hidden wings or secret histories. A familiar shape making me reach for a familiar story.

I wrote: What if the echo is in the observer?

For once, the smaller handwriting appeared above mine.

Then why did you draw the door twice?

I looked back through the pages. I had drawn it three times.

In the Triceratops sketch. In the landscape behind Parasaurolophus. Now in the reflection.

I hadn't noticed the second one.

At the bottom of the water stood a squat, armoured silhouette. Something that looked built to stay exactly where it was.

Across its back was a final mark: a short horizontal stroke, blocking the doorway.

Under the drawing, one instruction.

Find what keeps it shut.