Massachusetts, 1851. Winifred Starbuck wants only one thing: to join her parents on their final merchant voyage --- from Nantucket Island to bustling San Francisco, then across the glittering Pacific to the distant ports of China. Yet renowned trade captains Nell and Peter Starbuck have forbidden their daughter from coming aboard on the adventure of a lifetime. So Winnie does what any strong-willed 18-year-old would do: she stows away. Once the ship sets sail, Winnie is plunged into turbulent waters, treachery, and the thrill of life on the high seas. As she drifts farther from shore, and closer to fabled Canton port, she uncovers a long-buried secret --- one that reveals the truth behind her parents’ desperate fear.

In 1846 Nantucket, Eliza Macy is struggling to conceal her financial trouble as she waits for her whaling captain husband to return from a voyage. In desperation, she turns against her progressive ideals and targets Meg Wright, a pregnant free Black woman trying to relocate her store to Main Street. Meanwhile, astronomer Maria Mitchell loves running Nantucket’s Atheneum and spending her nights observing the stars, yet she fears revealing the secret wishes of her heart. On a sweltering July night, a massive fire breaks out in town. With everything they possess now threatened, these three very different women are forced to reevaluate their priorities and decide what to save, what to let go, and what kind of life to rebuild from the ashes of the past.