Twilight Ghost by Magdalen Nabb
Carrie has seen what appears to be a child in the midst of a red glow standing at a window in her grandmother's house. She explores the house in an attempt to overcome her fear, but triggers a timeslip and becomes Edwina - the little girl from the window - who died in a fire in 1901. By author of award-winning Enchanted Horse. Ages 9-12.