In The Eyes of the Amaryllis, young Jenny Reade has been sent to an isolated Cape Cod home to care for her grandmother Geneva, who has broken her ankle. Jenny doesn't know her grandmother well and has never before seen the ocean. Years earlier, Jenny's grandfather, a sailor, drowned when his ship sank off the coast in a storm. Jenny's father, who was never able to come to terms with his own father's death, moved inland as soon as he was old enough. Now, a married man, he has never allowed Jenny to visit her grandmother or the family's ancestral oceanside cottage.
Jenny quickly realizes, however, that a broken ankle is the least of her grandmother's problems. Soon after her arrival, the old woman insists that Jenny accompany her on mysterious, evening scavenger hunts along the wind-swept beaches. Although Geneva's husband has been dead some thirty years, the woman searches, after every turning of the tide, for some gift from him and watches for some fragment of his former life to wash ashore.
At first Jenny fears that her grandmother is mad, until she begins to discover evidence that something extraordinary is indeed going on. While combing the shore, she and her grandmother meet Seward, who may or may not be a ghost sent to protect the sea's interest. Then, a few days later, Jenny finds the figurehead from the Amaryllis, her grandfather's lost ship. Her grandmother regards the figurehead as a gift from her long lost husband, a proof of his continuing love. Soon, however, it becomes clear that the sea wants the figurehead back, and that, if it isn't returned, the sea is perfectly willing to come and get it.