Summer of the Dragon by Elizabeth Peters

A good salary and an all-expenses-paid summer spent a sprawling Arizona ranch is too good a deal for fledgling anthropologist D.J. Abbott to turn down. What does it matter that her rich new employer/benefactor, Hank Hunnicutt, is a certified oddball who is presently funding all manner of off-beat projects, from alien conspiracy studies to a hunt for dragon bones? There's even talk of treasure buried in the nearby mountains, but D.J. isn't going to allow loose speculation -- or the considerable charms of handsome professional treasure hunter Jesse Franklin -- to sidetrack her. Until Hunnicutt suffers a mysterious accident and then vanishes, leaving the weirdos gathered at his spread to eye each other with frightened suspicion. But on a high desert search for the missing millionaire, D.J. is learning things that may not be healthy for her to know. For the game someone is playing here goes far beyond the rational universe -- and it could leave D.J. legitimately dead.