The Tintern Treasure by Kate Sedley

In this gripping medieval mystery, Roger the Chapman, a traveling peddler with a knack for solving crimes, finds himself embroiled in a dangerous quest for a legendary treasure hidden within the ruins of Tintern Abbey. As he navigates the treacherous landscape of 15th-century England, Roger must unravel a web of deceit, betrayal, and murder, all while confronting his own past and the secrets it holds. With the help of a colorful cast of characters, he delves into the abbey's dark history, uncovering clues that lead him closer to the elusive treasure and the truth behind a series of chilling events.