Emily finds two more files—one for her mom and another for Jake Windsnap. Documents in Emily’s file identify her as an experiment of some kind for the merfolk, and it’s clear from her mom’s file that the merfolk have been repeatedly wiping her memories and keeping her away from merfolk territory to keep memories of Jake from resurfacing. Feeling sick, Emily realizes Mr. Beeston has been spying on her and her mom, probably for Neptune. The girls try to swim to the prison where Emily’s dad is being held, but it’s too far. Stopped on a small island, Shona finds two nearly identical rocks and gives one to Emily. They are best friend pebbles that are a promise the girls will always be friends, and Shona says, “a promise that we’ll find your dad” (111).

Hoping it will trigger her mom’s memories, Emily brings her mom to a bay near Rainbow Rocks. When they get close, Emily’s mom suddenly remembers strong love and sadness, followed by the feeling it isn’t safe there. The two head home for afternoon coffee with Mr. Beeston.