Secret of The Desert Stone by Frank E. Peretti

Biblical archeologist Dr. Jacob Cooper arrives in Togwana with his children Jay and Lila and one goal-to discover the secret behind the two-mile-high Stone that has mysteriously appeared overnight. Who could have excavated, carved, and transported the colossal Stone? The Coopers' uneasiness soon turns into dread as they are watched and threatened by the country's new government and brutal dictator Id Nkromo.

Follow the Coopers as they race to solve the mystery of the desert stone!