"Seventeen-year-old Yena Bae is spending the summer in Busan, South Korea, working at her mom's memory-erasing clinic. She feels lost and disconnected from people, something she's felt ever since her best friend, Lucas, moved away four years ago without a word, leaving her in limbo. Eighteen-year-old Lucas Pak is also in Busan for the summer, visiting his grandpa, who was recently diagnosed with Alzheimer's disease. But he isn't just here for a regular visit--he's determined to get his beloved grandpa into the new study running at the clinic, a trial program seeking to restore lost memories. When Yena runs into Lucas again, she's shocked to see him and even more shocked to discover that he doesn't remember a thing about her. He's completely erased her from his memories, and she has no idea why. As the two reconnect, they unravel the mystery and heartache of what happened between them all those years ago--and must now reckon with whether they can forge a new beginning together."-- Provided by publisher.