"Maybe that rusty boat hangar looked like the entrance to a cave to her," he'd said. Maybe. If you were eight, and near-sighted, and nostalgic for places that you'd never been. But if the Glowworm Grotto actually exists, that changes everything. Olivia's ghost could be there now, twitching her nose with rabbity indignation - "But I left you a map!" Wondering what took us so long to find her."