The overseas success of Georgian-German novelist Nino Haratischvili’s 900-page epic The Eighth Life (2019), which followed a single Georgian family through the tumult of the 20th century, has prompted the translation of this shorter, more intimate 2011 novel about an on-off sexual relationship between two adoptive siblings. Set largely in Hamburg, it’s narrated by 36-year-old Stella, a slipshod journalist at “a medium-sized, mediocre newspaper” whose editor promises to put her in charge of the culture section if she can focus. But work – not to mention her husband and six-year-old son – soon go by the wayside when her ex-lover, Ivo, a war reporter raised as her brother, arrives in town after eight years incommunicado. Haratischvili’s scenario will appeal to fans of Leïla Slimani’s Adèle, which also involves a half-arsed hack whose clandestine sex life brings release from domestic and professional obligations. Stella’s appeal as a narrator rests on her chilly blasts of ennui. Here she is on her sister, a children’s author: “I found the staid conventionality she radiated almost intolerable.” And her husband, Mark, an award-winning documentary-maker? “I hated him for… his sympathetic manner, his strong sense of responsibility, his blamelessness.” When he serves wine in crystal glasses, she tells us damningly that he “always fetched these glasses with a view to us having special sex later on”. Stella mixes her frank account of the to-do stirred up by Ivo’s return – hotel-room assignations, missed school pick-ups, a him-or-me ultimatum from Mark – with the story of how she and Ivo grew up together after her philandering father slept with his mother. But as we yo-yo between time frames to see the fallout from their adolescent lust, Stella tiptoes teasingly around more deeply buried secrets, not least her part in the tragedy that first brought Ivo into her family. While the novel’s sexual voltage buoys you through its twists and turns, Haratischvili isn’t out only to portray middle-class marital and maternal strife. When Ivo urges Stella to join him on assignment to the Caucasus with an exiled musician he got to know in New York, the jolting gear shift into geopolitical drama crams practically another novel’s worth of characters into a quarter of the book’s length. For readers of The Eighth Life, it’s a return to expected turf, but it also feels like authorial bet-hedging about where the story’s strengths lie. My Soul Twin by Nino Haratischvili (translated by Charlotte Collins) is published by Scribe (£16.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply