Hannah doesn't get seasick, she gets landsick. Separated from the sea, hundreds of miles inland, she realizes if she doesn't go back to Boston, she will die.
Some people fear the sea, and are sick when they sail on it. Hannah needs the sea. She doesn't realize how much until she leaves it. When she's too old to live in the Boston orphanage where she's spent her life, she takes the orphan train out West, to Kansas, and gets more and more ill the farther she gets from the sea. She begins to shed tiny salt crystals, and strange flat translucent ovals, and food sickens her. Finally, one night she realizes that if she doesn't go back to the sea, she will die, and the couple she's been staying with agree to send her back.
When she gets there, she is able to find a job working as a scullery maid for a wealthy family in Beacon Hill. The household is in a turmoil — the Hawleys are returning from Paris, and the house must be made ready for them. The two huge eight foot Chinese vases that stand in the front hall arrive first, and must be cleaned and put into place. As Hannah helps with the vases, she is drawn to a part of the blue and white design that shows a fish's tail that rises above the waves. The scales on the tail look familiar somehow.
The next day, she meets the painter, Stannish Wheeler, who has been commissioned to paint a protrait of the three Hawley daughters. When she mentions to him that the vases are to be in the portrait, he looks at her oddly and says, "I'll bet you're fascinated by those vases, especially by the part of the pattern where the fish tail just breaks through the waves."
Hannah's blood runs cold. How does he know that about her, something she has never told anyone about? Why is she so strongly attracted to him? What's in store for her, and for him?