Rob and Hannah Wilson (twins, age 30) return from Europe in 2020 for their father's funeral. Dan Wilson, 70, will lie in a green cemetery full of twittering birds and sun-dappled shade, beside his second wife (or is she?) Nancy, who died in 2018 after 30 happy years together. Among two dozen mourners stands a beautiful and stylish angel from a parallel reality, wearing designer sunglasses and a Parisian outfit-ghostly alter ego of the twins' baby sister Klara, who died in 1979 while Dan Wilson served as a young soldier in Heidelberg. Claire (lost baby Klara's alter ego in a parallel reality) is classy, strong, calm-and invisible. She has a faint glow behind her, and is untouched by raindrops. Moving unseen through this tale, she plants Dan's journals and drops other clues to reveal her mission to Rob and Hannah. Hannah works for a Paris insurance firm, and is dating handsome young music producer Yves Cartier. Rob is a doctoral student at Frankfurt's Goethe University, dating attractive Elise Gillen of Luxembourg. Youthful Dan Wilson made a tragic decision on a famous bridge (Pont des Arts) one day in 1978. He abandoned the love of his life (French grad student Claudette Vervain), returned to his duty station in Heidelberg, and married a pretty Croatian-German girl named Stana Chetko. Claudette's doctoral thesis held stunning revelations about Leonardo da Vinci's art works in the Louvre Museum, from notebooks left by Dr. Benjamin Wandrous, a Jewish scholar murdered while the Nazis occupied France in World War Two. Soon after Dan left her, heart-broken Claudette went on a date with a young man who drank too much. Claudette died in a car crash, and her wonderful discoveries were lost forever. In a dark, forbidding mountain village near Heidelberg, Dan Wilson married Stana, who was pregnant with Dan's daughter. Dan's emotional nightmare included a loveless marriage; baby Klara's death at six months from a heart defect; the sociopathic bullying by Stana's father (an escaped Croatian Nazi-type war criminal); and Dan's unsympathetic, downright cruel Army superiors. On the windy, weepy, rainy 1979 night Klara died, a marvel happened in the village. In his mind and soul, Dan heard the voice of a mature, self-assured, and undoubtedly beautiful woman. Dan instantly knew she was Claire, an alter-ego of poor little Klara but alive and prospering in a parallel reality (another of infinitely many). Claire advised him these events were was in accord with a sublime plan, whose ultimate purpose was to save Claudette's and Wandrous' information about why Leonardo da Vinci worked until his 1517 death, with no pay or recognition, on a world-famous portrait seen today in the Louvre. Dan returned alone to civilian life in Salem, Oregon, where he remarried and had his two exceptional children, the twins Rob and Hannah. A promise had been given to Dan. At the moment of his death, he was transported back to that Bridge of Regret in 1978 where he'd left Claudette. In a new and different reality, the young soldier did not abandon her, but moved to Paris after his service and married her, while she continued her thesis work . The twins, guided by Claire's clues, pursue these mysteries to a climactic hour in the City of Light. Three worlds intersect briefly in a hidden Paris passage as they meet their siblings-Dan and Claudette's children, plus Klara's alter-ego Claire. Hannah's journey takes her through the famous Shakespeare & Company bookstore on the Left Bank, where she bumps into Claire for the first time under a sign that reads: "Be not unkind to strangers, lest they turn out to be angels." Claudette's thesis reveals the ultimate secret about Leonardo's portrait of a rather ordinary young housewife in early 1500s Florence. Touched by tragedy and joy forever codified in her eyes and enigmatic smile, a ghost of Lisa Gherardini del Giocondo gazes at us from a lost world-Mona Lisa.