Pushing the limits of human endurance, free divers can hold their breath for terrifyingly long times, more than 24 minutes. But what if a human could actually breathe underwater? In “At Sea,” Emma Fedor’s fantastical, genre-defying debut novel, Brendan, a member of the U.S. Special Forces, can do just that. Or can he? Set on Martha’s Vineyard, “At Sea” begins with an intriguing hook: A fisherman has spotted a man and child treading water in the middle of Nantucket Sound, nowhere near a boat or land.
