Mara found an old brass key in the pocket of her grandmother's winter coat. She did not know what it opened.
That evening she took the last ferry across the bay. An old man sat opposite her, turning a key in his fingers. It was exactly like hers! "Where did you find that?" he asked. "In my grandmother's coat," said Mara. "Then your grandmother was my best friend," he said. "My name is Aldo. Sixty years ago we locked a box under the old pier."
The next morning, at low tide, they found the box. Inside were two paper boats and a note: "We'll sail again." Aldo laughed and cried. Mara folded a new boat, and they sailed it together.