Abbey Is Missing — Dorothy Woolfolk

Donna Rockford and her sister Abbey take off for the desolate hills of Colorado with their mountain climbing club! When the group realizes they're neat an abandoned town, Dead Man's Gulch, they decide to explore it, and spend the night in an old hotel. But the next day, when Abbey and Donna take a hike in the mountains, Abbey vanishes...

Frantic, Donna begins tracking clues and questioning suspects. Then one of the suspects is injured, and Donna finds herself under investigation! She needs all her strength and courage to find her sister, and prove her own innocence.