The Dog Who Would Not Smile — Stephen A. Bly

Nathan T. Riggins panicked as he hurried from one empty building to the next. Where was everyone? How could everybody in a whole town just disappear?
In the deserted Post Office, bags of unopened mail lay everywhere. With increasing dread, he looked through the stacks of letters. There it was--his own letter to his parents telling them he was coming. No wonder they hadn't waited for him here in Willow Creek. Now what should he do?
Nathan set out across the Nevada desert in search of his parents only to come face to face with one danger after another--Indians, a masked gunman, a blinding sandstorm, a rattlesnake. Meanwhile, a strange dog that seemed to adopt him kept coming to his rescue.