In 1952, vivacious former model Ruth Macallister receives a cryptic letter from her fraternal twin sister, Iris, whom she hasn't seen since they parted ways in Italy twelve years prior under less-than-amicable terms. Iris had fallen in love with a boozy diplomat, Sasha Digby, who later became a spy for the Soviet Union. Now Iris wants Ruth to visit her in Moscow, where she's expecting her third child. Fearing that her sister may be in danger, Ruth teams up with an FBI agent posing as her husband and travels behind the Iron Curtain in the hopes of rescuing Iris and her family. Beatriz Williams grounds her twisty plot in the fraught relationship between the estranged sisters, resulting in a suspenseful narrative that sparkles with psychological insight. (BH)