Night of the living chatchke

"Nancy Drew travels to Turkey with her father, attorney Carson Drew, who plans to negotiate the sale of an ancestral estate belonging to one of his clients. When Nancy finds that mysterious artifacts have been disappearing from the estate, she turns her suspicions to Harland Severino, a rich man who desperately wants to purchase it. Nancy does some sleuthing that leads her beneath the property into an environment no one could've guessed what lay there: the ancient ruins of a city long forgotten by time, filled with priceless ancient artifacts that grave robbers will do anything to get at!" -- from publisher's web site.