Uneasy Relations — Aaron Elkins

Buried ceremoniously, high in a cave on the Rock of Gibraltar, lies the skeleton of a human woman, clutching the skeleton of a part-human, part-Neanderthal child. Fascinated, Professor Oliver jumps at the chance to visit the site. But two deaths, possibly murders, have rocked Gibraltar. As Oliver tries to piece things together, he's about to fall for some deadly tricks. After all, unlike the Gibraltar Boy, he's only human.