As an aging saber-toothed tiger prowls prehistoric Florida, a young paleo-Indian struggles to escape his tribe's superstitious beliefs. Is the old cat the ghost of a saber-tooth slain four years earlier, come to take its revenge? Is the wanderer Fonn that same ghost, in the shape of a young woman? Dour, the shaman, insists that these things are so, but 12-summer-old Thom wonders: Fonn seems real to him, and she says that the cat is only an animal, huge and ferocious but mortal. As Bonnie Pryor did in Seth of the Lion People (1988), Denzel paints the prehistoric scene in some detail but is less conscientious about creating believable early people--""It is the mark of Smilodon,"" Fonn remarks learnedly, looking at a pawprint. Nonetheless, Denzel offers another well-paced adventure that, like his Boy of the Painted Cave (1988), captures a transition between old and new, ignorance and knowledge. In the end, Thom escapes Dour's influence, and he and Fonn witness an epic battle between Great Claw (the last giant sloth) and the wounded, rabid saber-tooth. Their deaths mark the end of the age of giant mammals; for readers who don't get the point, the author suggests in an afterword that we too shall pass.