Having fled the man she was engaged to marry, young Lady Aurelie Capet finds her way to the Grand Palace on the Thames boardinghouse and manages to fake her way into becoming a temporary lodger under the name Mary Gallagher. Anxious to head to Boston and her only surviving family, she is only waiting to liquidate some assets for the trip when Christian Hawkes crashes into the dockside inn, bleeding from a knife wound. The motley inhabitants rally to his aid, mistaking him for an expected new guest. But it is Aurelie, posing as the widowed Mrs. Gallagher, who volunteers to watch over the feverish man, realizing that her recent misfortune has shown her how tough she is in dire straits. From then on, the tension ratchets up, both from the couple’s magnetic sexual and emotional attraction and the reader’s awareness of his real mission—finding her—and his chameleonlike skills. As always, Long’s style, with its evocative phrases, casts a spell. She is also deft at weaving the protagonists closer to each other while building a sense of dread: How will the knot be unraveled, and will the truth of their past entanglements with the same man lance old poisons or infect their budding love? But the normally nimble writer missteps in forcing a conversation about Aurelie’s flight after the third-act breakup, worsening the black moment through a choice that is inexplicable and unnecessary and potentially hurts the hero’s heroic status. The eventual resolution involving the villain is somewhat hollow as well, because it makes Aurelie’s recent past a tool to serve the hero’s character arc. The familiar members and new guests of the boardinghouse provide needed comfort even as the new couple add a frisson of excitement and uncertainty.