An expedition to investigate an old sunken ship teaches Peggy lessons about herself.

When archaeologists discover a two-hundred-year-old shipwreck, Peggy Henderson decides she'll do whatever it takes to take part in the expedition. But first she needs to convince her mom to let her go, and to pay for scuba diving lessons. To complicate matters even more, Peggy's Great Aunt Beatrix comes to stay, and she's bent on changing Peggy from a twelve-year-old adventure-seeking tomboy to a proper young lady. Help comes in the most unlikely of places when Peggy gets her hands on a copy of the captain's log from the doomed ship, which holds the key to navigating stormy relationships.