Courage by Darkness — Jeri Massi

Jean Derwood's biggest hope is that one day she will do something brave or heroic and prove that she is not a coward. Chances of heroism seem pretty slim in the quiet town of Peabody, Wisconsin, but then a letter arrives for the family, inviting them down to Uncle Rufus's farm in Alabama. As Jean soon learns, the farm is next to an abandoned hunting lodge and no more than a mile from the turning and twisting passages of Limestone Cave.

To make things even more interesting, a stolen jewel called the Winchester Beryl is said to have been hidden in the area. The police are still combing the mountains for the jewel thieves. Afraid, on the one hand, that the Lord will not send her an adventure and yet afraid that He will, Jean's first chore is to convince her parents to let her stay at the farm.