The Wanderer begins with Sophie describing how the ocean is calling her, and her intense longing to get out on the open seas, but this admiration and passion for the ocean is quickly undercut when she recounts a nightmare she’s had. In it, a massive, lethal wave looms over Sophie, and right before it’s about to fall upon her and destroy her, she wakes up. Sophie feels instinctually pulled to the ocean, yet from the beginning of the book we get the sense that there’s also something very troubling and dangerous about her relationship with the water—she fears it, to some extent.
Sophie’s three uncles—Dock, Mo, and Stew—and her cousins Brian and Cody are planning to take a trip across the ocean in Dock’s boat (“The Wanderer”) to see Bompie, Sophie’s grandfather, who lives in England. Sophie wants to join them on the trip, partly because of her desire to get out on the open seas, but also to see Bompie, who everyone thinks is nearing the end of his life. The otherwise all-male crew is reluctant to let Sophie join because they think that, because she’s a girl, she’ll cramp the manly vibes of their trip, and that she’s not cut out physically and emotionally for the hard work and potential dangers involved in sailing a ship. She has her parent’s permission, however, and resists her fellow crewmembers’ complaints enough such that she gets herself involved in the trip, whether they like it or not.
After the crew make the necessary repairs to The Wanderer where it’s stationed in Connecticut, they get on their way towards England. In Connecticut (and during the trip in general) Sophie shows herself to be skilled at making repairs, and not nearly as useless as her crewmembers had thought. As The Wanderer gets on its way, a mystery about Sophie’s past makes itself apparent. The parents she’s been talking about all this time are actually her foster parents. What happened to her original parents? This is the question constantly on the tip of Cody and Brian’s tongue, and when they ask Sophie, she either avoids answering altogether or talks about a “little kid” whose parents died—but she never identifies herself as the little kid. Further, Sophie is always telling stories about Bompie’s life, but the rest of the crew thinks she’s just inventing them, since she’s never actually met him before.
After making stops at Block Island, Martha’s Vineyard, and one of the Fundy Islands in New Brunswick (Grand Manan), they finally get out on the open sea, heading straight for Bompie in England. On the way the entire crew is nearly killed, as an almost-deadly wave—resembling that from Sophie’s nightmare—strikes The Wanderer. Everyone survives, yet no one comes out of the experience the same. The Wanderer is largely a tale of how the crewmembers aboard the ship change from before the wave to after. In general, they become warmer to each other and more connected, whereas before they had taken their lives and their actions for granted.
When the crew arrives in England, they’re ecstatic to be back on land. They make their way to Bompie’s house, and it’s revealed that Bompie had sent Sophie letters telling her stories about his life—she hadn’t been making them up. Sophie then chats with Bompie, retelling to him all the stories he’d sent her—but there’s one which he does not recognize: when, as a child, he was at sea with his parents and they were swept away by a wave and drowned. Cody suggests that this story isn’t Bompie’s, but Sophie’s, and Bompie agrees. Sophie breaks down and cries, but she’s reached the end of her journey: she’s uncovered the truth of her past. She’s come to a more authentic and complete understanding of her history. By braving the ocean and surviving a wave similar to that which killed her parents, and coming to understand her identity better in relation to her old and new families (being finally able to tell them apart), she frees herself from the grips of a past which she had blocked out from her mind. Having discovered the truth, she can begin a new life.