Another freebie in the Dotsy Lamb travel mystery series, Death of a Lovable Geek
by Maria Hudgins.
The body of young Froggy Quale lies, covered by a blue tarp, in the pasture behind Castle Dunlaggan in the Scottish Highlands. Froggy was the on-site pollen and spore expert at the nearby archaeological dig and a graduate student who doesn't seem to have had an enemy in the world.
Dotsy Lamb, ancient and medieval history teacher from Virginia, and her friend Lettie are boarding at the castle while Dotsy works at the dig. They and the other guests are cared for in the ancient castle by its owners, William and Maisie Sinclair.
Suspicion for Froggy's murder falls on his roommate, Van Nguyen, a graduate student from America. Dotsy has become fond of both Froggy and Van and is sure Van can't be the killer. When the dig's director dies from poison mushrooms, Dotsy sees connections to the magic mushroom party at the dig and to ownership of castle lands.
This is a suspenseful brainteaser that pits the brains of an American history teacher against the dark secrets of a tragic family history.