On the first morning of summer, Pip ran down to the beach and almost tripped over her dog Biscuit. He had a green bottle in his jaws, washed up between two rocks. Pip pried it open. Inside was a paper torn down the middle: half a coastline in faded blue ink, and one word left at the rip. It said HARBOR.

Pip knew the old harbor. It was a twenty-minute ride up the coast road. She grabbed her bike from the porch, tucked the map in her pocket, and whistled. "Come on, Biscuit. The other half of this map has to be somewhere." Biscuit barked and chased after her wheels.

Halfway to the harbor, Biscuit veered off the road, nose down, dragging Pip toward a sandy gully. He had caught a scent. At the bottom sat a half-buried wooden chest, its lid stuck under a tangle of driftwood and seaweed.

Pip and Biscuit hauled the driftwood away and forced the lid open. Inside, wrapped in oilcloth, lay the exact missing half of the map. Joined together, the two pieces showed a trail of dotted ink leading to a lighthouse on the far point. "That's where we're going," Pip grinned.