Harper Proulx is convinced that without knowing her anonymous sperm donor father, she can't know herself. When a chance Instagram post connects Harper to a half sibling, she joins her newfound half siblings on a voyage to Hawaii to face their father. The events of that summer, and the man they discover-- a charismatic deep-sea diver obsessed with solving the mystery of a fragile sunken shipwreck-- will force Harper to face some even bigger questions: Who is she? Is she her DNA, her experiences, her successes, her failures? Who she is in dark times? Who she might become after them?