Ex Marks the Spot by Gloria Chao

For Gemma’s whole life, it has always been her and her mom against the world. As far as she knew, all her grandparents—and thus her ties to Taiwanese culture—were dead. Until one day when a mysterious man shows up at her door with two shocking things: the news that her grandfather has just recently passed, and the first clue to a treasure hunt that Gemma hopes will lead to her inheritance.

There’s just one major problem: to complete the hunt, she has to go to her grandfather’s home in Taiwan. And the only way Gemma can get there is by asking her ex and biggest high-school rival, Xander, for help. But after swallowing her pride, she finds herself halfway across the world, ready to unearth her life-changing prize. Soon Gemma discovers that the treasure hunt is about much more than money—it’s about finally learning about her family, her cultural roots, and maybe even finding true love.