In the third installment of the Treasures of Halstead Manor series, Brooke Sumner carefully avoids and ignores Storm Whitlock—her replacement in Caspar's mysterious treasure-hunting group—and instead focuses on her antique shop.

Caspar's next assignment entails finding the second half of a key lodged in the spine of their most recent discovery, and Brooke reluctantly rejoins the group to keep Storm in check. But as they delve into their next adventure, she realizes that Storm might not be who she thought. While the mysterious key unlocks a vault of secrets, Brooke discovers that treasure-hunting together has unlocked her heart toward Storm and the rest of the group. With priceless artifacts at their fingertips, the team discovers that the true treasure is so much more.

The Hidden Key of Brooke Sumner combines mystery, friendship, and romance, sending the reader on an action-packed adventure around the globe in pursuit of a treasure that could fall into the wrong hands. Susan L. Tuttle spins a story with relatable characters and an engaging mystery that will keep readers turning pages late into the night.