Young Indiana Jones Series by William McCay, Les Martin

In 1913 in Luxor, Egypt, an ancient ring leads Indy to a hidden tomb and into terrifying adventures with a German archaeologist.

An adventure featuring the young Indiana Jones, who with his friend, Herman, visit Stonehenge, where Herman's father is on an exploratory dig. Strange things start to happen which seem to suggest that black magic is being performed around the old stones and then Indiana meets the arch druid.

Visiting Turkey in 1914, young Indiana Jones and his pal Herman stumble onto an evil cult that lives in a secret underground city.