Sixth grader Gwen Baker is puzzled. Why does her history teacher, Mr. Sharp, continue to arrive at school with strange bruises? Why does he seem lost in another world so often? She knows how it began - lightning hit the school one evening when Mr. Sharp was working late. He rescued a homeless man who had wandered into the teacher workroom for shelter. But why do new bruises continue to dot his arms for weeks? Classmates spread rumors about the cause. Only Gwen and her friends Nathan and Libby have the courage to pursue the true cause that lies within the mystery of the teacher workroom. Their...