Stuck at her grandma’s quiet beach house with no Wi-Fi, twelve-year-old Delia Martinez expects the slowest summer ever—until a mysterious hand-drawn map falls from a dusty library book.
The X on the map leads her past the moonlit pier to a buried stone “tower” and a hidden door that clicks open at her touch. Inside waits the long-forgotten Sandcastle Society, a secret room filled with seashell mosaics and decades of kid-made journals begging for a new chapter.

Join Delia as she redecorates the hideout, uncovers snapshots of summers past, and writes a riddle that will launch the next explorer’s adventure. It’s a story about finding friendship, chasing curiosity, and learning that even the loneliest vacation can sparkle with magic.