Nigeria by Tom Wangler

The year is 1975. In the remote African savannah region of northern Nigeria, a lone American Peace Corps Volunteer mysteriously disappears while searching for a secret oasis. It was an innocent-enough camping trip that went horribly wrong. In a race against time, three of his friends—two Peace Corps volunteers and a Marine security guard from the U.S. Embassy—embark on a search and rescue mission like no other. Their manhunt takes an unexpected turn when they stumble onto an ancient and deadly side of Nigeria's past. Survival soon becomes the primary goal for the search team as they close in on their objective, become isolated, and face unimaginable terror.