Jean Kwok – born in Hong Kong, raised in Brooklyn, based in the Netherlands – had a hit a decade ago with Girl in Translation, a novel inspired by her own immigrant experiences. For her new book, a bestseller in the US, she’s drawn on a further harrowing personal history: in 2009, her brother, Kwan, disappeared while piloting a plane and was never seen alive again.

Searching for Sylvie Lee imagines a hunt for a missing sibling. Sylvie and Amy are Chinese-American sisters – but Sylvie was raised by relatives in the Netherlands and goes back to visit her dying grandma. Then she vanishes.

Sylvie is brilliant: clever, beautiful, successful, with a rich husband and good job. Her little sister, Amy, is stuttering and timid, until she finds herself travelling across the world to work out what’s happened. Secrets pile up, as chapters move between Amy’s search and Sylvie’s account of the months leading up to her disappearance.

She carefully maintains the mystery of Sylvie’s disappearance till the final chapters

Kwok attempts to reflect the languages her characters speak – Chinese, English, Dutch – being fluent herself in all three. Searching for Sylvie Lee is enriched with proverbs and phrases, from the sublime – a mother referred to as “my heart stem” – to the ridiculous – “a floppy dick in rosewater”. These add an unusual flavour but can also jolt the reader. And what I assume is an attempt to translate some Dutch has a fatally stiffening impact on the dialogue: “Has all hope sailed?” and “goes it all right?” do not sound like they come from the mouths of globetrotting thirtysomethings.

Stylistically, Kwok’s work is held in a fine balance between coolly measured literary prose and a pacier thriller. She carefully maintains the mystery of Sylvie’s disappearance till the final chapters, where accusations, twists and revelations suddenly come thick and fast. Some are satisfyingly shocking; others stretch believability. Occasionally the manoeuvres needed to keep the wool over readers’ eyes result in clunky elisions, diversions or plot devices. Take Sylvie starting cello lessons, for instance: really, who begins to learn an instrument while visiting a dying grandmother?

Villains tend to be very villainous (there’s a wicked stepmother straight out of central casting); beautiful people are very, very beautiful. Indeed, the book is at its weakest in moments of fervid romance: the chiselled jaws, parted lips and tight muscles tip towards steamy cliche.

Kwok is mostly more interesting and subtle than that. She is astute in constantly turning over the characters’ misconceptions of one another, especially the sisters who each see in the other what they lack in themselves (Sylvie yearns for Amy’s capacity for love; Amy hankers after Sylvie’s confidence). Kwok’s exploration of the lies we tell by putting on a mask for the world, or simply avoiding speaking the truth, is often elegantly unrolled.

• Searching for Sylvie Lee by Jean Kwok is published by John Murray Press (£16.99). To order a copy go to guardianbookshop.com. Free UK p&p over £15