The Assassin King — Will Adams

When the body of Dunstan Warne is found buried in one of his own fields, it triggers not only a murder investigation led by outcast detective Ben Elias, but also a race to find the prize Warne had dedicated his life to searching for – the fabulous crown jewels and priceless other treasure lost in the Wash by King John over eight hundred years before. As Warne's niece Anna teams up with celebrated local TV reporter Oliver Merchant in an effort to solve the ancient mystery, they quickly discover that Warne Farm holds other shocking secrets too, and that there are powerful forces who'll stop at nothing to keep them hidden.