Confidence by Denise Mina

In this "edge-of-your-seat" thriller and sequel to the Reese Witherspoon x Hello Sunshine book club pick Conviction (The Los Angeles Times), Anna and Fin find themselves on another breathtaking chase across Europe—and another race to save their own lives. 

Deception. Theft. Murder. All you need is confidence.

Anna McDonald has made a terrible mistake. She has forced her blended family to vacation together. The weather is bad, her daughters are bored, and her ex-husband still insufferable. Oh, and Fin Cohen brought his latest girlfriend, too. So when news of a shocking kidnapping breaks, Anna and Fin do the responsible thing. They take off to solve the case. 

Lisa Lee, a young YouTube star, has vanished after answering the door to what she thought was a pizza delivery. Police suspect her dad or the delivery guy, but in Lisa’s last known video she ventured into an abandoned chateau in France, where she uncovered a priceless artifact. Anna knows they must find this young woman before it’s too late. To do so, they need to track down that treasure, a casket that could hold answers to the greatest questions ever asked.

But Anna and Fin might have misunderstood the stakes of the game. Soon, they find themselves mixed up with some very dark characters, on another thrilling chase across Europe—and another race to save their own lives.