The envelope showed up on a Tuesday, sea-blue and soft at the corners. The handwriting belonged to Theo, Mara's best friend from when she was eleven. Twenty years of silence, and now one line inside: "I found the map of Saltreach in my mom's attic. The lighthouse is still unfinished. Want to build it?" Mara sat down hard and read it three more times.

Mara put the letter in a drawer and tried to forget it. But that night she pulled out an old shoebox and found a crayon drawing she'd made at ten: a striped lighthouse, two stick kids waving from the top. On the back, in her kid handwriting: "OURS." She didn't sleep at all.

Mara drove to Saltreach the next weekend without telling Theo. The cliff path was overgrown but still there. At the top sat a low stone foundation, half-built and buried in grass. Someone had been here recently. A thermos sat on the wall, still warm.

Mara waited by the warm thermos until footsteps came up the path. It was Theo. He froze, then grinned. "I've been working this foundation alone for weeks, hoping you'd come." Mara picked up a trowel. They built the rest together that summer, and lit the lamp at dusk. Out in the harbor, boat after boat flashed their lights back.