one of the sea is a mystery about thirteen-year-old twins keke and kurtis March. when creepy things start happenings while they’re visiting their eccentric auntie gwendolyn, the twins suspect it’s more than a coincidence. so with the help of keke’s best friend melody arnold, and melody’s mute little brother buddy, the kids will have to solve the mystery of the weird laughter and creepy faces at the castle march