From New York Times bestselling author Jessie Burton comes a stunning debut middle grade novel and a story of friendship, priceless treasure, and powerful magic.

When Bo Delafort finds treasure on the muddy bank of the River Thames, her life turns upside down. A solid silver circle, encrusted with pearls and edged in rubies, the jewel is worth more security and comfort than her family has ever known. The magic of the river runs in this treasure, and Bo wonders why it chose her to find it.

But when its reappearance is discovered by someone who knows its hidden power, Bo is plunged into a centuries-old mystery with a dark secret at its heart.

For fans of Katherine Rundell and Philip Pullman's The Ruby in the Smoke, Hidden Treasure is a classic in the making: an adventure with a rip-roaring plot, spine-tingling twists, and an unforgettable cast of characters.